Vermillion County lies in the western part of the U.S. state of Indiana between the Illinois border and the Wabash River. As of the 2020 census, the population was 15,439. The county seat is Newport. It was officially established in 1824 and was the fiftieth Indiana county created. Vermillion County is included in the Terre Haute, Indiana, Metropolitan Statistical Area. The county contains seven incorporated towns with a total population of about 9,900. as well as several unincorporated communities; it is also divided into five townships which provide local services. An interstate highway, two U.S. routes, and five state roads cross the county, as does a major railroad line.

The Terre Haute Metropolitan Statistical Area, also known as the Wabash Valley, is the 227th largest Metropolitan Statistical Area (MSA) in the United States. Centering on the city of Terre Haute, Indiana, it was originally formed by the United States Census Bureau in 1950 and consisted of Vigo County. As surrounding counties saw an increase in their population densities and the number of their residents employed within Vigo County, they met Census criteria to be added to the MSA. Four Indiana counties are now a part of this MSA.