No Zarahemla for Iowa
Revelation given in Nauvoo in March 1841. History of the Church 4:311-312.
There has never been an official name of Zarahemla, Iowa. Before Nauvoo was settled by the Mormons the local Mormons called themselves citizens of Zarahemla but that was before this revelation. The locals (non-Mormons) didn’t like the idea of the Mormons renaming their area and called it Montrose. Subsequently the LDS Church called one of their wards by the name of Zarahemla.