What counties in Kentucky border Indiana?

The Ohio River defines the border between Kentucky and Indiana, so technically, the answer is no county has a land border with Indiana. Practically speaking, though, from west to east, 13 counties are adjacent to the Hoosier State: Union, Henderson, Daviess, Hancock, Breckinridge, Meade, Hardin, Jefferson, Oldham, Trimble, Carroll, Gallatin, and Boone.