The original building for the Grain Valley Branch was built in 1976. The building was 2,400 square feet. At the time, the population of Grain Valley was approximately 1,300. In 1989, the building was enlarged to 4,200 square feet, and the population was approximately 1,900. In the most recent census, which was 2010, the population was approximately 12,854. That's an increase of 149.1% since the 2000 census.