This example dataset shows deaths from a cholera outbreak in 1854. John Snow used this data in conjunction with local pump locations as evidence that cholera is spread by contaminated water. A digitised version of the data is available online, courtesy of Robin Wilson (robin@rtwilson.com).

This example data set shows bike thefts in Vancouver in 2011. The data was obtained from a 2013 Vancouver Sun blog post by Chad Skelton.

This example data set shows the location of traffic signals in Toronto. The data was obtained from Toronto Open Data. The idea to use this data set comes from this R-bloggers post by Myles Harrison.