The Chicago Marathon attracts 40,000 runners, of which 10,000 come from countries other than the US. Course records stand to Paula Radcliffe at 2:17:18 from 2002, and to Dennis Kimetto, who ran 2:03:45 in 2013.
You can also subscribe to the AIMS calendar in your calendaring application of choice, whether on your phone, tablet or computer. Simply subscribe to webcal://aims-worldrunning.org/events.ics in your calendar app.