Hartford City is a city in the U.S. state of Indiana, and the county seat of Blackford County. Located in the northeast central portion of the state, the small farming community experienced a 15-year “boom” beginning in the late 1880s. The Indiana Gas Boom was caused by the discovery of natural gas in the area, and it caused the community to transition from an agricultural economy to one that also included manufacturing. After the boom, the town lost some of its manufacturers and workforce.