What does "entering Houston City limits"?

Question

when i'm driving from my work that is in Houston, I come across a few signs on the road that say "Entering Houston CIty limit"

what does this mean? i thought i was already in the city of houston.... so why does it say that i'm entering it?

Answer 1

Houston is a large town with many surrounding towns that were outside the town limits yrs agon bit now that Houston has grown it grows around a town that it can't incorporate.