K-57 is a 31.2-mile-long (50.2 km) north–south state highway in the U.S. state of Kansas. K-57's southern terminus is at K-4 in Dwight. The northern terminus is at U.S. Route 77 (US-77) north of Junction City. The highway intersects Interstate 70 (I-70) in Grandview Plaza; at the intersection, I-70 is also the route of US-40 and K-18. K-57 overlaps US-40 Business (US-40 Bus.) from I-70 northbound to North Washington Street in Junction City. North of Junction City, the highway passes through Milford State Park where it crosses the Milford Lake Dam. The majority of the highway is two-lanes except for the section from J Hill Road in Grandview Plaza to the junction with K-244 which is four-lanes.