Grayslake is located in north Illinois. Grayslake is part of Lake County. Grayslake has 9.87 square miles of land area and 0.21 square miles of water area. As of 2010-2014, the total Grayslake population is 20,863, which has grown 12.74% since 2000. The population growth rate is much higher than the state average rate of 3.62% and is higher than the national average rate of 11.61%. Grayslake median household income is $87,967 in 2010-2014 and has grown by 20.27% since 2000. The income growth rate is lower than the state average rate of 22.70% and is lower than the national average rate of 27.36%. Grayslake median house value is $217,400 in 2010-2014 and has grown by 12.70% since 2000. The house value growth rate is much lower than the state average rate of 34.33% and is much 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 Grayslake is better than the state average in quality. The Grayslake area code is 847.