Maryland Route 23 (MD 23) is a state highway in the U.S. state of Maryland. The state highway runs 20.58 miles (33.12 km) from U.S. Route 1 (US 1) in Hickory north and west to the Pennsylvania state line near Norrisville, where the highway continues as Pennsylvania Route 24 (PA 24). MD 23 is an L-shaped highway in northwestern Harford County that consists of two major sections. Between US 1 and MD 165 in Jarrettsville, MD 23 is marked east–west along a two-lane road with partial control of access named East–West Highway. From MD 165 to the state line, the state highway is marked north–south along Norrisville Road, a rural two-lane highway that passes through the villages of Madonna and Shawsville. The two sections of MD 23 are connected by a short concurrency with MD 165.