Wednesday, February 5, 2014

The Map that Saved the London Underground

The 1914 Wonderground Underground Map, a mixture of cartoon, fantasy, and topological accuracy, by Macdonald Gill. 

I love this map, and this article!  Of course, one of the reasons I love the article (link below) is that it's about the London Underground, and it incorporates a lot of interesting historical background and contextual detail.  Another reason is that it is written in a rather meandering way, going off on tangents that eventually lead back to the story at hand.  Naturally, I admire this style of writing!  And, most unusually, I have nothing more to add.  Thanks, Andrew M., for sending the link to the map, which allows you to zoom around the map and see all the incredible detail.

Tuesday, January 28, 2014

Carbon Footprint by Zipcode

Source: UC Berkeley CoolClimate Network, Average Annual Household Carbon Footprint (2013)

Well, we city-dwellers have known all along that it is more environmentally beneficial to live in high density urban areas.  But now we have the unfortunate evidence that, alas, any carbon footprint benefits accruing to cities are more than offset by the much higher carbon footprint of our suburban counterparts in the nearby hinterlands, and based upon a visual inspection of the mapped data, it appears that the wealthier suburban communities are definitely the bigger energy hogs than their poorer suburban neighbors or rural areas.  There are a series of cool interactive maps (at and thanks, Tom Paino, for sending me the link) allowing you to zoom into any zipcode in the continental US and see how the annual household carbon footprint has been tallied, considering transportation, housing, food, goods, and services.  My zipcode, 10033 in Washington Heights, NYC, for example, is rather carbon thrifty, at 34.6 metric tons of CO2 equivalent, while just across the Hudson River in 07632 Englewood Cliffs, NJ, it is nearly double at 69.5, and in Old Westbury, on Long Island to the east of NYC, it is 95, almost triple. 
Baltimore City, MD (21201) is positively parsimonious at 25, and Baltimore shows up on the map as a green oasis in a sea of reds and oranges, denoting the surrounding suburban household carbon footprints double that of the inner city.   There was one thing that I question on this map and that is there is no legend, so we cannot see what the class ranges are for each color.  When you touch on each zipcode, the stats for that zipcode pop up, but it seemed to me that the same color represented different ranges, perhaps dependent upon the state.  Therefore it is difficult to make any consistent inferences based on the zipcode color, which obviously can be somewhat misleading in making visual comparisons. 
There are two other interactive maps: Average annual household energy (electricity, natural gas, other) carbon footprint by zipcode (where, again the contrast between Washington Heights in Upper Manhattan around 6 and Old Westbury at 16 is amazing!).
The third map is average monthly vehicle miles traveled per household by zipcode, (and of course in many parts of NYC, households have on average as low as 0.1 vehicle per household.  In other words, in many parts of the city, only one in 10 households has a car, on average.  The vehicle miles traveled is figured by multiplying vehicle miles traveled per month by the number of vehicles per household.  I found the assumptions of this calculation a little odd – nearly every zipcode in the country had households driving about 1,200- 1,400 miles per month, and I think there should be much more variation in this figure.  Only in some isolated areas in the western and northern US were households driving 1,500-1,700 miles per month, otherwise it seems that every household puts on essentially the same mileage.  I think if you live in NYC and are crazy enough to have a car there, the last thing you would be doing is sitting in your car racking up 1,200 miles a month.  If so, that’s about all you would have time to do traveling at the snail’s pace that is NYC traffic!  That’s an average of 40 miles per day, and virtually no one within the city would drive a 40 miles per day commute or just go joy-riding around for 40 miles per day. 
But other than those relatively minor cavils (and knowing how difficult it is to keep a nation-wide study consistent when there is such extreme variation across zipcodes) the maps are fascinating and the study seems sound. 
This shows how the suburban areas create a much higher carbon footprint than the cities or rural areas, from Philadelphia to New York City. 
Here’s the abstract from the paper the maps in which the maps appear:
“Which municipalities and locations within the United States contribute the most to household greenhouse gas emissions, and what is the effect of population density and suburbanization on emissions? Using national household surveys, we developed econometric models of demand for energy, transportation, food, goods, and services that were used to derive average household carbon footprints (HCF) for U.S. zip codes, cities, counties, and metropolitan areas. We find consistently lower HCF in urban core cities (40 tCO2e) and higher carbon footprints in outlying suburbs (50 tCO2e), with a range from 25 to >80 tCO2e in the 50 largest metropolitan areas. Population density exhibits a weak but positive correlation with HCF until a density threshold is met, after which range, mean, and standard deviation of HCF decline. While population density contributes to relatively low HCF in the central cities of large metropolitan areas, the more extensive suburbanization in these regions contributes to an overall net increase in HCF compared to smaller metropolitan areas. Suburbs alone account for 50% of total U.S. HCF. Differences in the size, composition, and location of household carbon footprints suggest the need for tailoring of greenhouse gas mitigation efforts to different populations.”

Frequently asked questions about the paper (and including limitations of the study and urban planning implications) are at:

 The American Carbon Footprint

Also, here’s another cool website with interactive maps, showing global carbon footprints by current emissions, per capita, intensity, and cumulative emissions, going back to 1850 at the dawn of high industrialization.  Very enlightening!

And we couldn’t forget Danny Dorling’s amazing global cartograms of CO2 emissions, from the Worldmapper team at

Thursday, January 16, 2014

12 Maps that Changed the World

 The Waldseemuller Map of the World, #5 in The Atlantic’s list of 12 Maps that Changed the World

“This work by the German cartographer Martin Waldseemuller is considered the most expensive map in the world because, as Brotton notes, it is "America's birth certificate"—a distinction that prompted the Library of Congress to buy it from a German prince for $10 million. It is the first map to recognize the Pacific Ocean and the separate continent of "America," which Waldseemuller named in honor of the then-still-living Amerigo Vespucci, who identified the Americas as a distinct landmass (Vespucci and Ptolemy appear at the top of the map).  The map consists of 12 woodcuts and incorporates many of the latest discoveries by European explorers (you get the sense that the woodcutter was asked at the last minute to make room for the Cape of Good Hope). ‘This is the moment when the world goes bang, and all these discoveries are made over a short period of time,’ Brotton says.”
(See also for a discussion of The Fourth Part of the World: The Race to the Ends of the Earth, and the Epic Story of the Map that Gave America its Name, a book about the Waldseemuller map and its importance, as well as about The Globemaker’s Toolbox, another recent book about the map. 
When I mentioned this website from The Atlantic, “12 Maps that Changed the World,” to some friends (non-map people), they were rather astonished.  They had a hard time grasping the concept that maps could change the world, or even be very important to our lives in any way.  Check out this (article from The Atlantic) at  NOTE: Best viewed in Chrome; Internet Explorer seems to distort the images, for some odd reason.  Thanks, Christopher Herrmann, for sending me the link.

I would agree with most of their picks - who could dispute the importance of maps by Ptolmey, Al-Idrisi, the T-in-O Mappa Mundi, Waldseemuller, Mercator, the Gall-Peters projection, and so forth - although a couple of their top 12 seem rather removed from global significance, to my mind, but nevertheless they are all fabulous maps/mapping efforts.  My list would probably be a bit different, and I don’t think I would be able to pick just 12!  (I have a problem restricting myself!)  I might have added in or substituted the following 12 maps (in no particular order of importance):

John Snow’s 1854 map of cholera cases in mid-19th century London, which was one of the most significant jump starts to medical geography/spatial analysis, and the discovery/evidence of the links between disease and environment (see my blog post on John Snow’s map). 

John Snow’s map, pinpointing cholera deaths and the location of public water pumps in Soho, London. 

The US Public Land Survey System (PLSS), begun in about 1785 at Thomas Jefferson’s behest, which platted townships and sections in most of what is now the United States, and which basically laid an imaginary grid over the whole country in the spirit of the rational age of the Founding Fathers.  The PLSS shaped the landscape of the entire continental US (outside of the original 13 colonies and a few other earlier-settled eastern states);

1885 Township platting of Kent, Ohio

The UK Ordnance Survey (definitely!) which was extremely influential and innovative, and set the standard for many national mapping programs (including the massive effort of mapping the Indian subcontinent), and introduced many ground-breaking surveying and cartographic techniques.  The OS maps are still vitally important today, and many visitors to the UK who use the maps marvel at the extreme detail and the very large scale – some series are 6 inches to the mile! See

Detail of an Ordnance Survey map in the UK, the original impetus of which was military defense and intelligence gathering.  The village of Wooten Bridge, surveyed in 1862.

On a more localized level, in terms of impact, the maps resulting from the surveyor’s mapping of the Mason-Dixon Line between north and south U.S., with its very real ramifications on people’s lives in the 19th and even 20th centuries.  The Mason-Dixon line was surveyed in 1763-1767 in response to a border dispute between some of the American colonies prior to the Revolutionary War.  It has become understood in the conventional wisdom to symbolize a cultural boundary between the northern and southern states, and also served (unintentionally) as a rough line of demarcation separating slave-holding states from states where slavery was illegal.  This line was unofficially extended out as the country grew westerly, and the subsequent maps that resulted depicted the country divided into slave and non-slave states, as famously seen in the Abraham Lincoln painting of signing the Emacipation Proclamation;

The map prepared by the surveyors Mason and Dixon, on behalf of the Royal Astronomical Society in Greenwich, UK, using some instrumentation and methods not readily available to colonial surveyors, which increased the accuracy of the survey. 
 Lincoln signing the Emancipation Proclamation, featuring the map showing the country divided into slave and non-slave states.  The map appears at the bottom right corner of the painting, and was made by the U.S. Coast Survey in 1861 using census data from 1860, and shows the relative prevalence of slavery in Southern counties that year.  The painting is now hanging in the U.S. Capitol Building. 

The 1811 Commissioner’s Plan for the proposed gridiron layout of NYC, which more or less created the real estate frenzy that continues to define New York City, not to mention the uniquely simple and topography-erasing street pattern of Manhattan, which persists to this day.  The grid plan for NYC was in keeping with the US PLSS, and influenced many cities to adopt the rationality and ease of wayfinding of the grid, thus rejecting the more organic form that most European cities had as an artifact of the mediaeval era. 

The 1811 Commissioners’ Grid Plan for Manhattan

The map that al-Hassan ibn-Muhammad al-Wezaz al-Fasi (aka Leo Africanus) prepared for Pope Leo X in about 1520, based on geographical knowledge from of Leo Africanus’s own extensive travels, and which showed as never before to Western eyes the reality of northern Africa and the Middle East.   See

A detail of the 1520 Leo Africanus map, derived and compiled from a collection of maps Leo was traveling with when he was captured by pirates in the Mediterranean Sea.  These maps helped save Leo’s life from the pirates, since he had no one to ransom him, and so was otherwise worthless to them, but he did have the maps, which the pirates recognized as valuable.  They sold Leo Africanus (and the maps) to the Pope as a slave. 

In that vein, I would also have to include The Catalan Atlas, 1375, by the Jewish cartographer Abraham Cresques of Majorca, Spain, which was partially a type of Portolan navigational chart, a cutting-edge and more accurate technique at that time, and the map was also considered to be the most complete picture of geographical knowledge as it stood in the later Middle Ages.  See:

Detail of the 1375 Catalan Atlas

Speaking of Africa, how could we neglect to mention the famous Berlin Conference of 1884-1885 (also known as the Congo Conference) where Africa was divided up on a map amongst all the major European powers of the day.  That dividing-up map still reverberates today with the borders of countries having nothing to do with tribal areas, language or cultural groups of the indigenous peoples, dividing people who should have been kept together, and putting together people who didn’t want to be together, and based solely on “equitably” spreading out the “spoils” of African resources amongst the European colonials who had footholds in various parts of Africa by then.  Many consider this map to be the un-doing of Africa.  See

The Partition of Africa - The Berlin Conference Map of 1885

The 1602 Matteo Ricci map of the world.  Ricci was a Jesuit priest who traveled as a missionary to China in 1583.  In 1602, Ricci and his Chinese collaborators created the first map of the world in Chinese, now called “The Impossible Black Tulip of Cartography,” because of its rarity, importance, and exoticism.  Its name in Chinese is Kūnyú Wànguó Quántú; literally “A Map of the Myriad Countries of the World”; in Italian, “Carta Geografica Completa di tutti i Regni del Mondo;” or “Complete Geographical Map of all the Kingdoms of the World,” printed in China at the request of the Chinese Emperor.   

This is a later variation of Ricci's map.  The original 1602 Ricci map is a very large, 5 ft (1.52 m) high and 12 ft (3.66 m) wide, xylograph of a pseudocylindrical map projection, showing China at the center of the known world.  Its projection is similar to the 1906 Eckert IV map.  It is the first map in Chinese to show the Americas.  It was originally carved on six large blocks of wood and then printed in brownish ink on six mulberry paper panels, similar to the making of a folding screen.  See:

Olaus Magnus’s 1539 Carta Marina – a map of the ocean showing the Northern Lands.  See It is a very large map, about 5 ½ feet wide by 4 feet high.  “Magnus' map of the great northland was a fantastic achievement, its stature undeterred by the liberal use of sea monsters and other fanciful creatures.  The detail in the coastlines (as well as the depiction of currents between Iceland and the Faroe Islands) as well as interior features make these among the most detailed maps of the north yet printed in the 16th century.”

Detail of the 1539 Carta Marina, showing the northern islands of Scotland/Norway/Iceland (Orkneys, Faroe, Shetland).  

Joseph Minard’s 1869 flow map showing a detailed and longitudinal view of Napoleon’s 1812 march into Russia, which ended so disastrously for the French troops.  There are a number of variables portrayed in this 2-dimensional figure, which very beautifully conveys a complex set of information, according to the wiki entry for Minard:
§  the size of the army - providing a strong visual representation of human suffering, e.g. the sudden decrease of the army's size at the crossing of the Berezina river on the retreat;
§  the geographical co-ordinates, latitude and longitude, of the army as it moved;
§  the direction that the army was traveling, both in advance and in retreat, showing where units split off and rejoined;
§  the location of the army with respect to certain dates; and
§  the weather temperature along the path of the retreat, in another strong visualisation of events (during the retreat "one of the worst winters in recent memory set in").
Étienne-Jules Marey first called notice to this dramatic depiction of the fate of Napoleon's army in the Russian campaign, saying it "defies the pen of the historian in its brutal eloquence"[ Edward Tufte says it "may well be the best statistical graphic ever drawn" and uses it as a prime example in The Visual Display of Quantitative Information.
Howard Wainer identified Minard's map as a "gem" of information graphics, nominating it as the "World's Champion Graph
Minard was a pioneering cartographic and graphic designer, creating some of the first maps using pie graphs and other then-novel ways of mapping data. 

Minard’s flow map/diagram of Napoleon’s 1812-1813 march into Russia.

The Blue Marble satellite image of Earth - In some ways, these “pictures” of the whole earth from space have been instrumental in revising the average human’s mindset about our puny and tenuous existence in the universe, promoting the opposite of a geo-centric outlook, while at the same time reminding us earth-dwellers of our possibly unique place in the scheme of things and how fragile our planet actually is.  “This NASA moving image, recorded by satellite over a full year as part of their Blue Marble Project, shows the ebb and flow of the seasons and vegetation. Both are absolutely crucial factors in every facet of human existence -- so crucial we barely even think about them. It's also a reminder that the Earth is, for all its political and social and religious divisions, still unified by the natural phenomena that make everything else possible.” 

The Blue Marble satellite image of Earth

Worthy Runners-Up:

Charles Booth’s 19th century Poverty Maps of London, perhaps the first thematic maps with extensive use of socio-economic mapping, and his exhaustive ground-truthing methods of information gathering. 

Danny Dorling and teams’ Worldmapper Atlas of global conditions, using his amazingly effective and innovative cartogram technique.  
For more of Dorling’s work, see:
World Population by Country

Baron Alexander Von Humboldt’s isotherm map of temperature.  He developed the first isotherm maps as well as some other interesting new ways of geo-visualizing natural data in 2-dimensions.  He focused mainly on the New World, and was an inveterate traveler, being in many cases the first person mapping areas in South America and other parts of “The Kingdom of New Spain,” including Mexico, Texas, and parts of what is now the American Southwest.  He was also possibly the first person to proclaim that the continent of South America “fit” into the shape of Africa, and at one time they were probably joined landmasses.  There is an important Pacific current named after him, a cold current from Antarctica that comes up the west coast of South America and allows penguins to thrive in the Galapagos Islands on the Equator. 

First map of isotherms, showing mean temperature around the world by latitude and longitude. Recognizing that temperature depends more on latitude and altitude, a subscripted graph shows the direct relation of temperature on these two variables

Dr. Robert Perry’s 1844 maps of fever epidemic as connected with socio-economic and housing conditions in Glasgow, Scotland.  One of the first of its kind, and pre-dates the influential John Snow cholera maps by a decade, and the Charles Booth Poverty Maps by 40 years.  The map uses local medical reports, statistical tables and a color-coded map of the city to highlight the link between poor sanitation, poverty, and poor health.  It is an excellent example of early thematic mapping, and pre-dates both Charles Booth’s Poverty Maps of London (1886-1903), and John Snow’s cholera maps of Soho, London (1854).  Perry’s map, with different neighborhood areas colored differently to designate the severity of the epidemic, made it obvious that the effects of the epidemic were not distributed evenly throughout the city, but disproportionately affected the poorest, most densely settled areas, where as many as 20% of the population had succumbed to the disease.  See more on Robert Perry and the 1843 fever epidemic at Also see

Detail of the Fever Map, showing fever cases

German propaganda maps from the 1930’s which helped sway opinion as to the righteousness of Germany occupying neighboring countries to allow for their famous “elbow room” to grow the German race and reclaim formerly German territories. 

Typical propaganda map symbols: (a) arrows represent pressure on Germany from all sides; (b) circle signifies the encirclement of Germany before and after WWI; (c) pincers personify the pressure against Germany from France and Poland from the west and east.

Of course, my list is heavy on the historically significant maps, and unfortunately this means that I have given short shrift to modern-day cartographers and geovisualizers, mainly because they haven’t had sufficient time to demonstrate their importance yet!  There are all kinds of potentially influential maps being produced today, which is, of course, part of what my blog attempts to bring to light. 

In 2010, the British Library had an exhibit on the World’s Greatest Maps.  For their picks, see:

Monday, January 13, 2014

Impressive Events of 2013, in geo-images

2013 in pictures

For all you extreme meteorological/geological events geeks, here are some amazing images of noteworthy events that took place in 2013.  The geographer-at-large blog seems to be on a roll of re-capping the year gone by, so here is another retrospective view of 2013.  The captions and text explanations of the images are in Dutch (oh! Excuse me!  Flemish – it’s a Belgian website) but I think the pictures speak for themselves.  And they are truly magnificent – a sobering reminder, if one is needed, of the beauty and the power of the forces beyond our control.

Friday, January 3, 2014

Best maps of 2013

“The image above is a screenshot from an amazing interactive global map of near-real-time wind pattern forecasts, based on data from the Global Forecast System. Cameron Beccario, inspired by last year's extremely popular U.S. wind map, built this visualization using D3 and other javascript modules. The interactive version is really fun to play with by turning the globe with your mouse, and the patterns are nothing short of mesmerizing. It's maps like these that make us really want to learn how to code.”

We are starting off the New Year with Wired Science’s Best Maps of 2013.  Or, as they titled them, “The Most Amazing, Beautiful, and Viral Maps of the Year.” A great selection, and of the 15 maps they featured, 3 are about New York City.  I found this one, NYC Henge, to be particularly interesting. 

“Twice a year, the setting sun lines up with the street grid of New York City's Manhattan, creating an incredible show and a free-for-all for amateur photographers. The phenomenon is known as Manhattanhenge, but the map above, dubbed NYCHenge and made by Javier Santana shows when and where the show can be caught all across New York City, any day of the year.”

Saturday, March 30, 2013

Cartographies of Life and Death: John Snow

John Snow, ‘Intimate Mixture of the Water Supply of the Lambeth with that of the Southwark and Vauxhall Company, 1854’ from On the Mode of Communication of Cholera, 1855.  LSHTM Library & Archives
“The second edition of Snow's inquiry was greatly expanded to include two maps – incidentally, the only two of his career.  Snow intended this map of the water supply in South London to be the centrepiece of his study – often termed The Grand Experiment.  It involved a mammoth on-foot investigation of 32 sub-districts of South London, supplied by two different water companies drawing water from different parts of the Thames – one polluted with contaminated water.  Snow showed that those residents supplied by the polluted source were several times more likely to contract cholera.  This demonstrated Snow's intuitive understanding of epidemiological principles: the groups exposed and not exposed to the contaminated water were very similar in every other respect, and large numbers were involved.”  From the London School of Hygiene and Tropical Medicine’s Exhibit on Dr. John Snow, on the 200th Anniversary of his birth in 1813. 

I am not sure how I missed THIS important milestone, but March 15th, 2013 was the 200th anniversary of the birth of Dr. John Snow (1813-1858), the 19th century London anaesthesiologist who is considered to be the father of epidemiology and has become an iconic figure in public health.  He famously mapped the victims of a cholera epidemic in relationship to the locations of public water sources, and in the process, made the connections between the disease and contaminated water.  Until then, most medical professionals and the general public thought that cholera was caused by breathing unhealthy “miasma,” so rather than dealing with the root problems of a water-borne disease, they were under the mistaken impression that it was spread by air, and focused their attention to dealing with that problem instead of worrying about the water they were drinking. 

Snow prepared this version of the Broad Street map for a report to go before the Board of Health.  The map shows his original and innovative contribution to the field of disease mapping. The subtle inclusion of a dotted black 'Voronoi' line indicating the equidistant walking points between pumps helped to demonstrate Snow's theory that the Broad Street pump was the origin of the epidemic.
William Farr, “Diagram Representing the Mortality from Cholera in Different Elevations, 1848–1849” from Report on the Mortality of Cholera in England, 1840–50.  Wellcome Library, LondonFarr's Report offers some exceptional visual explanations of cholera mortality data. Contrary to Snow, Farr's analysis was leading him to the conclusion that elevation above sea level was the key factor in the communication of cholera.  Whilst his diagram clearly shows the relationship between lower ground elevation and higher mortality, this association was due to differences in water sources in these locations.  It is a reminder of how visualizations containing false associations have the power to mislead us. 
Right now at the London School for Hygiene and Tropical Medicine, an exhibit has been mounted detailing the detective story behind Dr. Snow’s map, and the influence his map has had in the world.  The hypothesis Dr. Snow was attempting to test involved much more than the mapping exercise, obviously, as important as that map was.  The map was based on a meticulous recording of all the cholera deaths in the Soho neighborhood, and some impressive footwork investigating from where various residences and institutions got their water.  So his analysis wasn’t just based on simple distance proximity, as it was discovered that many of the larger commercial establishments and so forth had their own private water supply, even though they were in close proximity to what turned out to be the culprit public water pump. 
From Mark Monmonier's seminal (1991) book "How to Lie with Maps"

Of course, one of the abiding drawbacks to Dr. Snow’s map was the fact that it is essentially a dot density map, and as has been noted by many cartographers, a dot density map often portrays nothing more than the underlying population density – you can not generally infer any information about the actual rate or proportion of the variable being mapped.  So what looks to be a “hot spot” of the disease or other variable on the map may be nothing more than an indication that there is the underlying concentration of people there, and nothing useful can be gleaned about the variable of interest.  In the case of Soho, however, this was less important than it would ordinarily be, since Soho as a whole was very densely populated, and likely the entire area has a similar enough population density per square mile or per acre. 

The exhibit points out that it was a commonly held belief during the social and political unrest prevalent with the outbreak of the cholera epidemic that the disease was a scare tactic dreamt up by the government to keep people in line, or that the disease was invented (or actively disseminated to the poor) by those in power for nefarious purposes, or even that the disease didn’t really exist at all.  There were even popular songs and poems along these conspiracy-theory lines and broadsheets published, including ones such as Cholera Humbug!  The Arrival and Departure of the Cholera Morbus. These broadsheets denigrated public health officials’ efforts to stem and contain the disease, and encouraged popular resistance against the political and medical authorities.  Unfortunately, these same kinds of attitudes still prevail in many parts of the world today, most noticeably pertaining to AIDS and sexually-transmitted diseases. 

And for some interesting things about the data itself, see the UK Guardian’s DataBlog post at
You can download the actual data collected by John Snow and his associates and play around with it, creating new visualizations and aggregations, and see for yourselves how incredible a feat Dr. Snow’s analysis really was, given he accomplished all this by hand and on foot.  No computers, GPS, telephone surveys, or Twitter tweets tracking. 
There are a few highly readable books on the cholera mapping story, most notably “Ghost Map: The Story of London’s Most Terrifying Epidemic and how it Changed Science, Cities, and the Modern World,” by Steven Johnson (2007).  Another, more critical, account of this seminal mapping project forms the basis of Tom Koch’s “Cartographies of Disease: Maps, Mapping, and Medicine,” (2005), ESRI Press. 

Detail of Dr. Perry’s 1844 map of the fever epidemic in Glasgow.  This shows three of the districts most seriously affected by the epidemic, bordered by Stockwell Street, Bridegate Street, Trongate, and Saltmarket, right near where I used to live!  The dots represent the locations of the fever victims.  

John Snow’s map has been called The Map that Changed the World.  Most people (if they know about Dr. Snow at all) believe that his cholera map is the first example of disease data mapping for analytical purposes.  This is not the case, even though his map may be the most well-known and celebrated.  Not to take anything away from Dr. Snow, but a decade or so earlier, in 1844, a Glaswegian surgeon at the Glasgow Royal Infirmary named Dr. Robert Perry, mapped a fever epidemic in Glasgow (detail shown above), and used it to make connections amongst poverty, bad housing, poor sanitation and environmental conditions, and disease.
The exhibit ends with some more recent examples of disease data mapping, showing the important legacy of Dr. Snow’s work, and how maps continue to help us combat disease and understand the relationship between health and environmental and social conditions. 

Dr Vale Massey's Map showing trypanosomiasis areas and distribution of Glossina palpalis and moristans brought up to 14 February 1907 in the Belgian Congo, Africa.  1907, hand-drawn. LSHTM Library & Archives.
Early public health was arguably more concerned with the protection of British interests overseas rather than serving the well-being of local populations, as evidenced in this map of Sleeping Sickness in the Belgian Congo.  The map was used in Commonwealth Office meetings to highlight how the disease was spreading along the banks of rivers towards areas of British gold mining interest and the need for strategies to stop this.

Iraq malaria survey maps: Baghdad area. LSHTM Library & Archives.
The striking graphic nature of this map highlights the urban environment's hidden danger zones of disease.  The dark red areas denote extreme risk, pink high and green slight risk areas.

In 2010 after an earthquake had devastated the island of Haiti, the cholera bacillus appeared, perhaps associated with UN soldiers.  It contaminated water sources, resulting in an outbreak that killed over 7,000 people.  Cholera is still prevalent to this day returning after each rainy season.
Ludovic Dupuis, Ivan Gayton and Ruby Siddiqui from Médecins Sans Frontières (MSF) and Chris Grundy from LSHTM mapped and spatially analysed the outbreak in the hope of tracking how the outbreak was spreading.  

You can take a virtual tour through the John Snow exhibit at the LSHTM at

A review “The lie of the land: Mark Monmonier on maps, technology and social change,”
of Mark Monmonier’s books and ideas on mapping, including some words on the Snow map:

Thanks, Rafael Pereira of Urban Demographics, for pointing out the link to Dr. Snow’s birthday.