Sure but they like... Don't have to be. "We must defend Chicago from these Texans. All able-bodied loyal citizens with arms are requested to report for muster at for training on how to properly observe these Confederate scum to ensure they do not violate our laws" etc.

Throw in some reasonable pay for a couple weeks work and the like and I bet you could drum up a good sized force to ensure that the Texans behave themselves while they're the guests of Illinois.