Zip Code 61462 is located in the state of Illinois in the Davenport - Rock Island - Moline metro area. Zip code 61462 is primarily located in Warren County. The official US Postal Service name for 61462 is MONMOUTH, Illinois. Portions of zip code 61462 are contained within or border the city limits of Monmouth, IL, Little York, IL, . The area code for zip code 61462 is 309.