Although Metro Map Maker officially launched in September 2017, I didn't include a created_at field on maps until September 13, 2018.

I made efforts to determine how many maps had been created by those dates based on historical records, but they're only estimates based on the known number of maps on a certain date.

For example, there were 606 maps created by April 11, 2018 (218 days since launch), so I divided those 606 maps roughly evenly across all 218 days.