Zion was incorportated in the State of Illinois Lake County on March 31, 1902.
This is an article on the status of Zion Cityin 1905. It's from Leaves of Healing vol 16 p 802 - 1905
An Article from Munsey's Magazine Sept 1902 - A City of the Plains
The City Directories for Zion City from 1908-1922 - sorted by last name.