San Luis is a city in Yuma County, Arizona, United States. The population was 15,322 at the 2000 census. San Luis was the second fastest-growing place among all cities and towns in Arizona of any size from 1990 and 2000. According to 2005 Census Bureau estimates, the population of the city is 21,646. San Luis apartments for rent comparison page shows most up to date rent information on San Luis apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.