Republic is an unincorporated community in Marquette County in the U.S. state of Michigan. It is also a census-designated place (CDP) for statistical purposes, covering a narrow, roughly crescent-shaped area along several miles of M-95. Most of the CDP is within Republic Township, although a small portion of the CDP extends north into Humboldt Township
According to the United States Census Bureau, the community has a total area of 3.9 square miles (10 km), of which 3.6 square miles (9.3 km) is land and 0.3 square miles (0.78 km) (7.67%) is water.
As of the census of 2000, there were 614 people, 276 households, and 187 families residing in the community. The population density was 170.1 per square mile (65.7/km²). There were 356 housing units at an average density of 98.6 per square mile (38.1/km²). The racial makeup of the community was 98.05% White, 1.63% Native American, and 0.33% from two or more races.
There were 276 households out of which 26.4% had children under the age of 18 living with them, 52.5% were married couples living together, 10.1% had a female householder with no husband present, and 31.9% were non-families. 30.1% of all households were made up of individuals and 17.4% had someone living alone who was 65 years of age or older. The average household size was 2.22 and the average family size was 2.67.
In the community, the population was spread out with 21.2% under the age of 18, 4.9% from 18 to 24, 23.8% from 25 to 44, 25.6% from 45 to 64, and 24.6% who were 65 years of age or older. The median age was 45 years. For every 100 females, there were 90.7 males. For every 100 females age 18 and over, there were 87.6 males.
The median income for a household in the community was $24,545, and the median income for a family was $29,659. Males had a median income of $24,875 versus $18,472 for females. The per capita income for the community was $14,793. About 10.7% of families and 15.1% of the population were below the poverty line, including 19.1% of those under age 18 and 16.2% of those age 65 or over.