I think what happens is that every property manager and landlord lists on Craigslist, as well as a few other places. Craigslist is pretty much a superset of all

I think what happens is that every property manager and landlord lists on Craigslist, as well as a few other places. Craigslist is pretty much a superset of all apartment ads in the area. Some of these other sites copy Craigslist, and some just have duplicate postings put there by the landlords.