The Chicago Transit Authority (CTA) has a pilot program of just 42 bus stops with ID numbers to which you can text to find out when the next bus is coming.
“That’s not enough,” thought one developer. So, she [corrected, was “he,” sorry!] built a Google Maps app where anyone can find their favorite bus stop and print out tag to affix to the bus stop itself (using clear packing tape). It’s called CTASTOPID.
This is just another example of user generated geo-content!
Trivia: Chicago Transit Authority was the name of the band Chicago before it clipped it to just the city name. (I’m old - and I lived in Chicago for a few years during college.)