According to the United States Census Bureau, the city has a total area of 3.0 square miles (7.7 km²), of which, 2.9 square miles (7.5 km²) of it is land and 0.1 square miles (0.2 km²) of it (2.03%) is water.
There were 2,158 households out of which 31.2% had children under the age of 18 living with them, 50.1% were married couples living together, 10.8% had a female householder with no husband present, and 34.9% were non-families. 31.1% of all households were made up of individuals and 15.6% had someone living alone who was 65 years of age or older. The average household size was 2.37 and the average family size was 2.98.
In the city the population was spread out with 25.3% under the age of 18, 9.4% from 18 to 24, 26.9% from 25 to 44, 20.0% from 45 to 64, and 18.5% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 89.0 males. For every 100 females age 18 and over, there were 83.4 males.
The median income for a household in the city was $34,821, and the median income for a family was $43,313. Males had a median income of $33,971 versus $24,016 for females. The per capita income for the city was $20,872. About 6.6% of families and 10.0% of the population were below the poverty line, including 11.8% of those under age 18 and 8.0% of those age 65 or over.
Amtrak Train 51, the westbound Cardinal, is scheduled to depart Rensselaer at 8:20am on Monday, Thursday, and Saturday; Amtrak Train 851, the westbound Hoosier State, is scheduled to depart Rensselaer at 8:20am on Sunday, Tuesday, Wednesday, and Friday. Both trains go to Dyer and Chicago Union Station to connect with other trains.
Amtrak Train 50, the eastbound Cardinal, is scheduled to depart Dyer at 8:57pm on Tuesday, Thursday, and Saturday with service to Lafayette, Crawfordsville, Indianapolis, Connersville, Cincinnati, Maysville, South Portsmouth, Ashland, Huntington, Charleston, Montgomery, Thurmond, Prince, Hinton, Alderson, White Sulphur Springs, Clifton Forge, Staunton, Charlottesville, Culpeper, Manassas, Alexandria, and Washington, DC and continuing on to New York City.
Amtrak Train 850, the eastbound Hoosier State, is scheduled to depart Rensselaer at 9:41pm on Sunday, Monday, Wednesday, and Friday with service to Lafayette, Crawfordsville, and Indianapolis.