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 1500 to 1999 that do not have portions within the State Primary and State Secondary systems.
KY 1508
Kentucky Route 1508 is a rural secondary highway in southern Union County. The highway begins at KY 109 in the village of Grangertown west of Sturgis. The highway heads west and receives the west end of Old Providence Road, which leads to KY 923. KY 1508 heads west along the northern edge of the Big Rivers Wildlife Management Area and State Forest to Caseyville, where the route turns north and runs along the Ohio River. KY 1508 crosses an unnamed stream and passes the Union County Boat Ramp on its way to Mulfordtown, where the road veers away from the river. At Dekoven, the highway runs concurrently with KY 492 north to the latter highway's terminus at KY 667. KY 1508 continues northeast to its terminus at KY 109.
KY 1531
Kentucky Route 1531 is a rural secondary highway that begins in northeastern Bullitt County and ends in northwestern Shelby County, but the route spends almost all of its length in the city of Louisville in eastern Jefferson County. The highway begins at KY 1319 (Kings Church Road) near Whitfield. KY 1531 heads northwest along Dawson Hill Road then turns northeast onto Routt Road to enter the city of Louisville and Jefferson County. The highway crosses Wheelers Run and Back Run and meets the eastern end of KY 1819 (Brush Run Road) south of the Routt neighborhood of Louisville. KY 1531 follows Sheckels Run to its crossing of Cane Run and reaches KY 155 (Taylorsville Lake Road) south of Fisherville. The highway runs concurrently with KY 155 northwest across Floyds Fork of the Salt River to KY 148 (Taylorsville Road), with which the route heads east through Fisherville and across Floyds Fork again.
KY 1531 splits north from KY 148 onto Eastwood Fisherville Road, which crosses another Brush Run and passes under a Norfolk Southern Railway line. The highway crosses Shakes Run and Long Run and passes under I-64 with no access on its way to Eastwood, where the highway intersects KY 2841 and US 60 (Shelbyville Road). KY 1351 continues on Johnson Road, which parallels and then intersects an R.J. Corman Railroad Group line and passes to the east of Valhalla Golf Club. The highway crosses a third Brush Run and briefly follows a bend of Floyds Fork. KY 1351 veers northeast onto Aiken Road at the junction with that county road and reaches its northern terminus at KY 362, which heads west on Ash Avenue and northeast on Aiken Road, just north of the Jefferson–Shelby county line.
KY 1533
Kentucky Route 1533 is a rural secondary highway in northern Allen County. The highway begins at KY 234 (Cemetery Road) north of Settle and heads east as Meador Port Oliver Road. KY 1533 crosses Little Difficult Creek, intersects KY 101 (Smiths Grove Road) at Meador, and crosses Difficult Creek. The highway reaches its east end at KY 252 (Barren River Dam Road) south of the dam that impounds the Barren River to create Barren River Lake.
KY 1575
Kentucky Route 1575 is a urban secondary highway in the city of Somerset in Pulaski County. The west–east highway begins at KY 2227 and travels east intersecting KY 1247 before terminating at KY 39. It is known as University Drive for its entire length.
KY 1580
Kentucky Route 1580 is a rural secondary highway in the city of Somerset in Pulaski County. The west–east highway begins at KY 1247 and travels east until the end of state maintenance.