Kentucky supplemental roads and rural secondary highways are the lesser two of the four functional classes of highways constructed and maintained by the Kentucky Transportation Cabinet, the state-level agency that constructs and maintains highways in Kentucky. The agency splits its inventory of state highway mileage into four categories: The State Primary System includes Interstate Highways, Parkways, and other long-distance highways of statewide importance that connect the state's major cities, including much of the courses of Kentucky's U.S. Highways. The State Secondary System includes highways of regional importance that connect the state's smaller urban centers, including those county seats not served by the state primary system. The Rural Secondary System includes highways of local importance, such as farm-to-market roads and urban collectors. Supplemental Roads are the set of highways not in the first three systems, including frontage roads, bypassed portions of other state highways, and rural roads that only serve their immediate area.

The same-numbered highway can comprise sections of road under different categories. This list contains descriptions of Supplemental Roads and highways in the Rural Secondary System numbered 600 to 699 that do not have portions within the State Primary and State Secondary systems.

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Kentucky Route 600

Kentucky Route 600 is a state highway in Muhlenberg County that runs from Kentucky Route 831 to Kentucky Route 171 northwest of Clifty.

Major intersections

Kentucky Route 601

Kentucky Route 601 is a state highway in Muhlenberg County that runs from Kentucky Route 181 on the western Greenville city line to Kentucky Route 175 north of Graham via New Cypress.

Major intersections

Kentucky Route 602

Kentucky Route 602 is a supplemental road in Central City in central Muhlenberg County. The highway begins at KY 277 (River Road) in the north of downtown. KY 602 heads north along an unnamed street and meets the western end of KY 3038 (Prison Road) before reaching its north end at KY 1031 (Second Street).

Major intersections

Kentucky Route 603

Kentucky Route 603 is a supplemental road in Owensboro in central Daviess County. The highway begins just south of a diamond interchange with the Wendell Ford Expressway, which carries US 60 and US 231 around the south side of Owensboro; the road continues south as Pleasant Valley Road No. 1. KY 603 passes through an S-curve and expands to a four-lane divided highway. The highway crosses over a CSX rail line and reaches its northern terminus at Fourth Street; this intersection also serves as the western terminus of KY 144.

History KY 603 was formed on September 12, 2011.

The original KY 603 ran from US 421 to KY 602 in Central City. This was given to the city on May 5, 1994, and is now Park Street.

Major intersections

Kentucky Route 604

Kentucky Route 604 is a supplemental road in Central City in central Muhlenberg County. The highway begins at US 431 (Second Street) just south of the U.S. Highway's four–loop ramp interchange with the Western Kentucky Parkway on the eastern edge of the city. KY 604 heads east and then turns north at Youngstown Road. The highway crosses over the parkway before reaching its north end at an acute intersection with US 62 (Everly Brothers Boulevard).

Major intersections

Kentucky Route 605

Kentucky Route 605 is a state highway that runs from Kentucky Route 1183 and Manton Road at Manton to U.S. Route 62 in far northeastern Bardstown via Botland and Woodlawn.

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Kentucky Route 606

Kentucky Route 606 is a state highway in Nicholas County that runs from Bald Hill Road northeast of Barterville to U.S. Route 68 southwest of Ellisville.

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Kentucky Route 607

Kentucky Route 607 is a rural secondary highway in southern Owen County. The highway begins at US 127 south of Monterey. KY 607 heads east along New Columbus Road, which immediately crosses Cedar Creek and has a hairpin at New. The route intersects KY 227 (Georgetown Road) west of Fairbanks, east of which the highway crosses Caney Creek. KY 607 meets the southern end of KY 1883 (Slatin Road) and meets the eastern end of KY 2018 (Swope Natlee Road) at Natlee, where the route crosses Eagle Creek. The highway continues through New Columbus to its eastern terminus at KY 330 (Owenton Road) at the Owen–Grant county line.

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Kentucky Route 608

Kentucky Route 608 is a state highway that runs from Frogtown Road at the Owen-Scott county line southeast of Natlee to U.S. Route 25 south of Stonewall.

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Kentucky Route 609

Kentucky Route 609 is a state highway in Pendleton County that runs from Kentucky Route 159 at Concord to Kentucky Route 177 east of Meridian.

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Kentucky Route 611

Kentucky Route 611 is a state highway in Pike County that runs from Kentucky Route 195 at Lookout to U.S. Routes 23 and 119 east of Jonancy via Lookout.

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Kentucky Route 612

Kentucky Route 612 is a state highway in northeastern Pike County that runs from Kentucky Route 468 south of Rural to Kentucky Route 292 northeast of Turkey Creek via Turkey Creek.

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Kentucky Route 613

Kentucky Route 613 is a state highway in eastern Powell County that runs from Kentucky Routes 11 and 15 at Bowen to Forestry Road No. 23 at the Menifee County line northeast of Old Lombard.

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Kentucky Route 614

Kentucky Route 614 was a state highway in Calloway County. It was formed in 1954, and ran from KY 280 east of Pottertown east via Poplar Springs Road. The road was given to Calloway County on June 16, 1985.

The original KY 614 ran from KY 11 in Stanton south to KY 1057; this became part of KY 213 when it was extended south.

Kentucky Route 615

Kentucky Route 615 is a state highway in central Powell County that runs from Kentucky Route 213 at Morris to Kentucky Route 599 northwest of Bowen.

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Kentucky Route 616

Kentucky Route 616 is a state highway that runs from Kentucky Routes 1029 and 2505 northwest of Fairview to Kentucky Route 875 southwest of Germantown via Abigail.

Major intersections

Kentucky Route 617

Kentucky Route 617 is a state highway in southwestern Robertson County that runs from U.S. Route 62 east of Kentontown to Kentucky Route 165 and Piqua Lane northwest of Piqua.

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Kentucky Route 618

Kentucky Route 618 is a state highway that runs from Kentucky Route 1781 at Broughtentown to Kentucky Route 1250 south of Spiro via Dog Walk and Quail.

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Kentucky Route 619

Kentucky Route 619 is a state highway in Russell County that runs from Kentucky Route 92 southeast of Montpelier to Kentucky Route 379 in downtown Russell Springs via Rose Crossroads and Jamestown.

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Kentucky Route 621

Kentucky Route 621 is a state highway in Simpson County that runs from Kentucky Route 103 southeast of Auburn to U.S. Route 31W north of Franklin.

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Kentucky Route 623

Kentucky Route 623 is a rural secondary highway in southwestern Spencer County. The highway begins at KY 48 (Highgrove Road) just north of the East Fork of Cox Creek, which forms the Spencer–Nelson county line. KY 623 heads north as Lilly Pike, which crosses the Salt River on its way to its north end at KY 44 (Mount Washington Road) east of Waterford.

Major intersections

Kentucky Route 624

Kentucky Route 624 is a state highway in far northeastern Trigg County and far northwestern Christian County that runs from Kentucky Routes 124 and 126 in Cerulean to Kentucky Route 91 and Old Princeton Road southeast of Bainbridge.

Major intersections

Kentucky Route 625

Kentucky Route 625 is a state highway in western Trimble County that runs to and from U.S. Route 421 via Mount Pleasant and Trout.Between Corn Creek Road and US-421 this route is closed to Trucks due to the tight switchbacks and narrow nature of the road.

Major intersections

Kentucky Route 626

Kentucky Route 626 is a rural secondary highway in southeastern Butler County and western Warren County. The L-shaped highway begins at a three-legged intersection with KY 1153, which heads west as Berry's Lick Road and north as Sandy Creek Road. KY 626 heads east along Berry's Lick Road through Turnertown, also known as Berry's Lick. The highway crosses Flat Rock Branch of Muddy Creek and intersects KY 79 (Russellville Road) at Davis Crossroads. KY 626 crosses Neils Creek west of Sharer, where the route has a brief concurrency with KY 1083 (Sugar Grove Road). The highway crosses the Butler–Warren county line and continues east on Jackson Bridge Road. KY 626 crosses the Gasper River and turns north at its junction with KY 2632 (Hammet Hill Road). The highway joins US 231 (Morgantown Road) to cross back over the Gasper River and turns north onto Highland Church Road at Hadley. KY 626 crosses William H. Natcher Parkway; on either side of the parkway, the route meets the eastern ends of a pair of frontage roads, KY 6140 (Frontage Road) and KY 6139 (Clifty Creek Frontage Road) on the north. The highway reaches its eastern terminus at KY 1435 (Barren River Road) at Rockland.

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Kentucky Route 628

Kentucky Route 628 is a state highway in southwestern Whitley County that runs from a dead end along Wolf Creek northeast of Ayres to U.S. Route 25W and Stringtown Road in Pleasant View.

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Kentucky Route 629

Kentucky Route 629 is a state highway in far eastern Ohio County and western Breckinridge County that runs from Kentucky Route 54 southeast of Fordsville to Kentucky Route 992 southeast of Mattingly via Rockvale.

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Kentucky Route 630

Kentucky Route 630 is a state highway in northern Hopkins County and south central Webster County that runs from Kentucky Route 262 and John Hardy Road south of Manitou to Kentucky Route 132 on the eastern Dixon city line via Manitou and Vanderburg.

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Kentucky Route 631

Kentucky Route 631 is a rural secondary state highway in Grayson County that runs to and from Kentucky Route 54 east and southeast of Short Creek via Duff.

Kentucky Route 633

Kentucky Route 633 is a supplemental state highway in far northwestern Adair County that runs from Cane Valley Road at the Taylor County line to Kentucky Route 55 and Cane Valley Church Road south of Coburg.

History The road originally ran from KY 61 east via KY 767 and north via Skinhouse Branch Road (former KY 2188). The road was extended east via KY 1913 to KY 1386, and replaced a section of it southeast to KY 61. By the 1970s, the road was truncated, with KY 767 and KY 1913 (which replaced the remainder of KY 1386 which was reassigned to a road in Scottsville) taking over parts of it and the separated section redesignated as KY 2188.

Kentucky Route 634

Kentucky Route 634 is a rural secondary state highway in far northern Taylor County and far southern Marion County that runs from Kentucky Route 744 northwest of Spurlington to Kentucky Route 289 southwest of Jessietown.

Kentucky Route 636

Kentucky Route 636 is a rural secondary highway in northeastern Spencer County and southeastern Shelby County. The highway begins at KY 248 (Briar Ridge Road) east of Taylorsville Lake. KY 636 heads north along Van Buren Road, which crosses Little Beech Creek on its way to Mount Eden, which sits on the Spencer–Shelby county line. The highway meets the eastern end of KY 1795 (Mill Road) on the Spencer County side and intersects KY 44 (Mount Eden Road) on the Shelby County side. KY 636 continues northeast as Back Creek Road, which crosses and briefly parallels another Little Beech Creek. The highway passes through Junte before reaching its northern terminus at KY 395 (Waddy Road) west of Harrisonville.

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Kentucky Route 637