Lorimor is a city in Union County, Iowa, United States. The population was 386 at the time of the 2020 census. Lorimor was founded by J.S. Loriā¦Lorimor is a city in Union County, Iowa, United States. The population was 386 at the time of the 2020 census. Lorimor was founded by J.S. Lorimor, who was given the honor of renaming the city, when the town grew after he gave land to the railroads as they traveled through town, in return for the railroad placing a water stop in the town. With the business from the railroads, and his 2,000-acre farm of bluegrass seed, the town was quite successful in its early years.