The City of Marengo was settled in 1835 near the Kishwaukee River in the far southwestern comer of McHenry County. Early industry centered on the town's windmill factory, steam flour mill, carriage factory, nursery, and a stone quarry that supplied stone for the buildings in Marengo and nearby Union.

Marengo is located along the 1-90 corridor, which provides easy access to and from Chicago, Rockford, and Madison, WI. The U.S. Route 20/90 exit for Marengo is also a major transportation and service interchange. Three major transportation corridors intersect in the city.

IL Route 176 and U.S. Route 20 (Grant Highway) connect to points east and west and intersect with IL Rte. 23, a major north-south corridor in the State. In addition, there are several airports in the area, including Chicago O'Hare International (40 miles) and Chicago Rockford International (30 miles).

The City experienced a steady rise in population growth over the last several decades. From 1990 to 2007, the community experienced an average annual growth rate of approximately 3%. With a current population of 7,637, the Chicago Metropolitan Agency for Planning projects Marengo to grow to 18,000 residents by 2030.

Several important businesses call Marengo home. These include Nissan Forklift (forklift manufacturer), Diversapack (flexible packaging), Danahar Motion (Electromagnetic, mechanical & control technology), and Engineered Polymer Solutions (paint resins).

In addition to public services offered by the City of Marengo, the community is served by the Marengo Fire District and the Marengo Rescue Squad District. Both provide full service emergency response.

Quality education is available to students of all ages including two public elementary school districts, an award-winning high school district, and a private elementary school. Two and four year colleges are available within easy driving distance.

Recreation and leisure activities are provided by the Marengo Park District with its 140 acre community park, including fitness center, public pool, daycare, and a wide range of recreation programs. The McHenry County Conservation District offers camping and nature appreciation programming in areas that showcase the natural beauty in the County.