51003 is zip code located in Alton, Iowa. The population is 1,585, making 51003 the largest zipcode in Alton and the 7th largest in Sioux County.
There are 1 public schools in 51003 with an average Homefacts rating of A. , and there are 1 registered sex offenders residing in the zip code 51003. Unemployment in 51003 is low.