Recently, I had the pleasure of presenting original research and maps about early modern death at the 2024 American Historical Association in San Francisco. I showcased maps between 1656 and 1680 based on general bill data. That span of years offered interesting data to showcase, including the major plague outbreak in London in 1665 and the Great Fire of London a year later in 1666. But how did I actually map these years?

Samuel Pepys is primarily remembered for his decade-long diary, which recorded major events in 17th century English history including the Great Plague Outbreak (1665).1 Just before the height of the plague, on September 7, 1665, Pepys wrote in his diary, “[I] sent for the Weekely Bill, and find 8,252 dead in all, and of them 6,878 of the plague; which is a most dreadfull number, and shows reason to fear the plague hath got that hold that it will yet continue among us.

As Death by Numbers has evolved and developed, there have been some slight changes to our workflow, which caused us to reconsider how to work through and present our data. One of those shifts came about because we set up our workflows using early 18th century bills as a model, before shifting to work with the bills from the mid and late 17th century. As a team, we quickly realized that the older bills were falling apart and had more missing information than the bills produced later.