GIS in Urban Planning and Public Health

The intellectual lineage connecting spatial analysis to public health is often traced back over a century before digital computers existed. During the 1854 cholera outbreak in London's Soho district, physician John Snow plotted the addresses of cholera deaths on a street map and observed that cases clustered tightly around a single public water pump on Broad Street; his subsequent argument that the pump's water source, contaminated by nearby sewage, was propagating the disease, helped undermine the then-dominant "miasma" theory that attributed cholera to bad air rather than contaminated water. Snow's map, discussed at length in Steven Johnson's The Ghost Map (2006), is frequently cited in GIS and epidemiology curricula as an early, manual precursor to modern spatial epidemiology — proof that mapping disease incidence against a candidate environmental cause could reveal patterns invisible in tabular data alone, decades before any formal GIS software existed to automate the technique.