An historical excerpt about the naming of Zionsville:
“The area showed little growth until 1852 when the Cincinnati, Indianapolis & Lafayette Railroad laid tracks across the Cross-Hoover lowland. Elijah Cross realized the importance of this historic event and contacted his friend and practical surveyor William Zion, in the new county seat Lebanon, and asked Zion to lay out a town using the railroad as the focal point. Zion plotted the town to be about a half-mile square with the eastern edge following the creek and the southeast corner following the bend. The railroad bisected the eastern side of the village and separated the business district of Meridian Street, later Main Street, from the residential section of the west. The town was to be named for Cross’s wife Mary, but when she heard of her husband’s choice she declined the honor. At a loss for a name, Cross asked the surveyor Zion to use his. Thus, the village was named Zionsville.”
The incorporation date of Zionsville: 1866 (village)

[more] http://www.bremc.com/zionsville/z-history.html