Hillsdale is a village in Rock Island County, Illinois, United States. The population was 588 at the 2000 census.Hillsdale is located at 41°36′37″N 90°10′25″W / 41.61028°N 90.17361°W / 41.61028; -90.17361.According to the 2010 census, Hillsdale has a total area of 0.779 square miles, of which 0.75 square miles is land and 0.029 square miles is water.As of the census of 2000, there were 588 people, 219 households, and 157 families residing in the village. The population density was 780.2 people per square mile. There were 237 housing units at an average density of 314.5 per square mile. The racial makeup of the village was 95.75% White, 0.51% African American, 0.68% Native American, 1.70% from other races, and 1.36% from two or more races. Hispanic or Latino of any race were 2.72% of the population.There were 219 households out of which 35.6% had children under the age of 18 living with them, 52.5% were married couples living together, 14.