Nauvoo is a small city in Hancock County, Illinois, United States, on the Mississippi River near Fort Madison, Iowa. The population of Nauvoo was 950 at the 2020 census. Nauvoo attracts visitors for its historic importance and its religious significance to members of several groups: The Church of Jesus Christ of Latter-day Saints; the Community of Christ, formerly the Reorganized Church of Jesus Christ of Latter-day Saints (RLDS); other groups stemming from the Latter Day Saint movement; and the Icarians. The city and its immediate surrounding area are listed on the National Register of Historic Places as the Nauvoo Historic District.

Hancock County is a county in the U.S. state of Illinois. According to the 2020 census, it has a population of 17,620. Its county seat is Carthage, and its largest city is Hamilton. The county is composed of rural towns with many farmers.