K-143 is a state highway in Saline County, Kansas. The route runs 4.658 miles (7.496 km) in a general north-south direction through lands mostly used for agriculture from an interchange at Interstate 70 (I-70) in northern Salina, Kansas to a junction with U.S. Route 81 (US-81). The southern part of the route is a four-lane divided highway while the rest is a two-lane highway. It has an annual average daily traffic (AADT) between 1,580 and 4,133 vehicles. The route is paved with three different pavement types, and is not a part of the National Highway System. It was first designated as US-81 Alternate in the early 1970s with the designation being changed to K-143 in the early 1980s.
K-143 begins at an interchange with Interstate 70 in the northernmost parts of Salina, Kansas. For the first 0.9 miles (1.4 km) of the route, the highway travels due north through commercial and agricultural land within the Salina city limits. A short distance after this, K-143 transitions from a divided four-lane highway into a two-lane highway. It then crosses the Saline River and continues north through primarily agricultural land north of Salina. At 2.7 miles (4.3 km), K-143 turns northwest and follows a gently curving path in that direction for the remainder of the route, ending at an interchange with US-81. The total length of the route is 4.658 miles (7.496 km). K-143 has an AADT of 4,133 vehicles in the southernmost 0.9 miles (1.4 km) of the route, with an AADT of 1,580–1,595 vehicles in the remainder of the route. The route is paved with a combination of full-design bituminous pavement, composite pavement, and partial-design bituminous pavement. K-143 is not a part of the National Highway System.