Early Rising Sun citizens sought to create a new county from Dearborn County with Rising Sun as its county seat, sending Colonel Abel C. Pepper to the state capital at Corydon in 1817 to petition for it. Although the request was denied, it began a 27-year rivalry with Lawrenceburg, then the county seat of Dearborn County. In 1836 Lawrenceburg, on Dearborn County’s eastern edge, lost that role to Wilmington because of Wilmington’s more central location. Advocates for the new county then gained leverage, since taking land from southern Dearborn County for Ohio County could help Lawrenceburg regain county seat status. An alliance with Lawrenceburg politicians followed, and in 1844 the Indiana Senate approved Ohio County and restored the Dearborn county seat to Lawrenceburg. Under the agreement with the state, Ohio County would build its courthouse without public funds. Colonel Pepper donated the land, and construction was completed in 1845. The original cost and architect are unknown, and the design may have come from a pattern book available at the time. Pinkney and John James, who laid out Rising Sun, may have chosen the Greek Revival style, accented by massive Dorian columns and noted for its classic temple form. It is the oldest courthouse in continuous use in Indiana and was extensively restored in 1987. To satisfy a state requirement that a county contain at least 400 square miles, Dearborn County was surveyed during low water on the Ohio River, creating the surplus land needed to form Ohio County.