High Quality Content by WIKIPEDIA articles! Rexburg is a city in Madison County, Idaho, in the United States. As of the 2000 census, the city population was 17,257. The city is the county seat of Madison County. Rexburg is the principal city of the Rexburg, ID Micropolitan Statistical Area, which includes Fremont and Madison Counties. As of the census of 2000, there were 17,257 people, 4,274 households, and 2,393 families residing in the city. The population density was 3,534.4 people per square mile (1,365.4/km²). There were 4,533 housing units at an average density of 928.4/sq mi (358.6/km²).