[citation needed] For most of its existence, First Financial operated largely in the Indiana and Illinois counties around Terre Haute, but two recent mergers greatly expanded the corporation's footprint into Kentucky.

[3] In October 2011, First Financial Corporation announced the pending acquisition of the Pontiac-based PNB Holding Company with its only subsidiary, the Freestar Bank, which has 13 offices in Central Illinois.

[4] In March 2013, First Financial Corp. acquired 9 branch offices in central and southern Illinois from Bank of America.

[5] On July 29, 2019, First Financial Corporation announced completion of its merger with HopFed Bancorp, Inc. (HFBC) and the merger of First Financial Bank with HFBC’s wholly owned subsidiary, Heritage Bank USA, based in Hopkinsville.

[8][9] The deal, which added branch locations in Hawesville, Lewisport, Madisonville, Cloverport and Bowling Green in Kentucky to the First Financial portfolio, was valued at $31.3 million dollars ($18.38/share).