After US 25 breaks away and goes north toward the Blue Grass Army Depot, KY 21 continues to the east and intersects US 421 in Bighill before ending at the Jackson County line.
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KY 21 passes through more farmland and woodland and winds southeast to its eastern terminus at the county line between Madison County and Jackson County.
Louisville, Kentucky | Kentucky | Lexington, Kentucky | University of Kentucky | Kentucky Derby | Versailles, Kentucky | U.S. Route 66 | U.S. Route 1 | Covington, Kentucky | Frankfort, Kentucky | Paducah, Kentucky | U.S. Route 6 | U.S. Route 101 | Route 66 | Bowling Green, Kentucky | U.S. Route 30 | New Jersey Route 4 | European route E65 | U.S. Route 40 | California State Route 1 | Barren County, Kentucky | U.S. Route 1 in Maine | Pennsylvania Route 309 | European route E18 | Ashland, Kentucky | U.S. Route 23 | Governor of Kentucky | European route E4 | U.S. Route 9 in New York | U.S. Route 11 |