Merrillville is a town in Ross Township, Lake County, Indiana, United States. The population was 35,246 at the 2010 census. Merrillville is in east-central Lake County, in the Chicago metropolitan area. On January 1, 2015, Merrillville became the most populated town in Indiana, as Fishers in Hamilton County was converted from a town to a city. The town serves as a major shopping hub for Northwest Indiana.
Merrillville is located at 41°29′08″N 87°20′07″W.
According to the 2010 census, Merrillville has a total area of 33.26 square miles (86.14 km2), of which 33.22 square miles (86.04 km2) (or 99.88%) is land and 0.04 square miles (0.10 km2) (or 0.12%) is water.
The town is centered on the intersection of U.S. Route 30 and Interstate 65.
The Lincoln Highway runs through Merrillville. The original alignment of Lincoln Highway is known as 73rd Avenue (also called Old Lincoln Highway) in Merrillville, while the current Lincoln Highway (US 30) is known as 81st Avenue. State Road 53 (Broadway) and State Road 55 (Taft Street) traverse the town from north to south.
Merrillville's asymmetric shape results in numerous boundaries with other municipalities.