Ithaca is a city in the U.S. state of Michigan. As of the 2000 census, the city had a total population of 3,098. It is the county seat of Gratiot County.
According to the United States Census Bureau, the city has a total area of 4.1 square miles (10.6 km²), none of which is covered by water.
As of the census of 2000, there were 3,098 people, 1,211 households, and 817 families residing in the city. The population density was 759.9 per square mile (293.2/km²). There were 1,289 housing units at an average density of 316.2 per square mile (122.0/km²). The racial makeup of the city was 96.03% White, 0.23% African American, 0.65% Native American, 0.36% Asian, 2.00% from other races, and 0.74% from two or more races. Hispanic or Latino of any race were 5.26% of the population.