Collinsville sits in Madison County, Illinois, about 12 miles east of downtown St. Louis across the Mississippi River. The city is part of the Metro East region — a cluster of Illinois communities that function as St. Louis suburbs while maintaining their own identities and significantly lower cost of living than the Missouri side. Interstate 55/70 runs through the city, providing direct access to downtown St. Louis in about 20 minutes. Collinsville is perhaps best known nationally for the Cahokia Mounds State Historic Site, a UNESCO World Heritage Site preserving the remains of the largest pre-Columbian settlement north of Mexico. The city also takes pride in the World's Largest Catsup Bottle, a quirky Brooks Foods water tower that has become an iconic roadside attraction. Neighborhoods range from older homes near the town center to newer developments on the east and south sides. Collinsville Unit School District #10 serves local students. The Gateway Commerce Center industrial park and the nearby Gateway Motorsports Park contribute to local employment, and many residents commute to St. Louis-area employers in healthcare, defense (Scott Air Force Base is about 20 miles south), and corporate offices. The Collinsville area benefits from Illinois' Metro East tax structure, where property taxes are higher than Missouri but sales taxes and the overall cost of living remain competitive.