Had you read my previous response in this very thread, you'd have noticed I was talking about metro Chicago.
That post must of been below mine. Am I supposed to read all posts before replying? Now interestingly the wiki article you link to says that the Chicago area encloses parts of 3 different states, Illinois, Indiana, and Wisconsin. While I thought the greater Chicago area may include Gary, Indiana, I didn't know it included any of Wisconsin.
So, to follow up, can a person take public transit to go from Wisconsin to Gary, Indiana? That is other than Greyhound and other national or regional transportation systems? After all your reply was about public transit. And the Greater Houston is also 10,000 sq miles.