1M Cities was a project to compile a list of the history of cities whose population has reached 1,000,000+. Starting in 1850, the graphic charts three stages of growth noting the largest city on each continent as the title changed hands as well as some important landmarks in urban growth. Though a seemingly simple task, no such list has been compiled before due largely to changing city sizes and definitions, and lack of census data and record keeping. To accommodate for these issues, a complex definition system was determined to provide fair and equal definitions of "city" that would provide for a balanced analysis. The chart notes the number of cities over 1,000,000 on each continent in the years 1850, 1950, and 2012 points special attention to four important facts:
1) in 775 CE, Baghdad became the first city with a population of 1,000,000
2) New York City became the fist city to hold the title in North America in the year 1880
3) London was the first city to cross the 5,000,000 mark in 1890
4) and in 1975, Tokyo grew to 20,000,000 becoming the first city to do so.