Thayer is located close to the center of Illinois. Thayer is part of Sangamon County. Thayer has 0.61 square miles of land area and has no water area. As of 2010-2014, the total Thayer population is 614, which has shrunk 18.13% since 2000. The population growth rate is much lower than the state average rate of 3.62% and is much lower than the national average rate of 11.61%. Thayer median household income is $52,750 in 2010-2014 and has grown by 25.50% since 2000. The income growth rate is higher than the state average rate of 22.70% and is lower than the national average rate of 27.36%. Thayer median house value is $82,900 in 2010-2014 and has grown by 33.93% since 2000. The house value growth rate is about the same as the state average rate of 34.33% and is lower than the national average rate of 46.91%. As a reference, the national Consumer Price Index (CPI) inflation rate for the same period is 26.63%. On average, the public school district that covers Thayer is much better than the state average in quality. The Thayer area code is 217.