Only U.S. prez born in Kentucky

ABE

Honest leader on the penny who split rails before splitting the nation.

This clue asks for the only U.S. president born in Kentucky, which is Abraham Lincoln—commonly nicknamed "Abe." The answer is shortened to just "ABE" to fit crossword space, a typical trick for famous figures with well-known nicknames. Since Lincoln was born in a log cabin in Hodgenville, Kentucky, the clue relies on that historical fact while keeping the answer concise.