I'm interested in the answer to this question too... we will probably move someday, and I've wondered about this. My educated guess would be yes, if you have the site totally prepared in advance and move the chickens overnight and have them in their new home by sunrise... otherwise I think it would be extremely stressful for them, and chickens aren't known for their ability to handle stress. But I definitely want to hear if anyone has tried it and what their experience was...
We'll be sad to have you leave the Colorado community.
Yes, you can but there are some things to take into consideration.
1. How long is the planned trip? 2 days or 3? Cages for the chickens that provide space for them to move around will be a must. Also, food and water for the trip. 4 large dog kennels will work if it's only for two days I think, but even that will be crowded.
2. It is July, so it will be hot in Colorado, and humid and hot in Illinois. They will need to acclimate so they won't get too stressed.
3. They will be bigger in July. They will be about 20 weeks old by then, and should be laying. You can expect them to slow down or even stop laying, especially if they get stressed.