[2] The land where Countryside sits was originally inhabited by the Potawatomi Indians and later by early American pioneers in the beginning of the 19th century.

Settler Joseph Vial and his family were among the first non-native people to settle in the Countryside area in 1833.

Land sold for only $2 an acre, which made areas such as Countryside a welcome respite from the congestion and industry in Chicago.

Despite the settlement of these early Countryside inhabitants, the area largely remained a quiet farming community until the post-World War II era when suburban areas such as Countryside began to experience explosive growth.

Groucho Marx later claimed that the brothers spent too much time at Wrigley Field watching the Chicago Cubs to make the farm economically viable.

According to the 2021 census gazetteer files, Countryside has a total area of 2.88 square miles (7.46 km2), all land.

The International Union of Operating Engineers (IUOE) Local 150 is based in Countryside at 6200 Joliet Road.

Pace provides bus service on routes 330 and 392 connecting Countryside to Summit, O'Hare International Airport and other destinations.