Maryland Route 146 is a state highway in the U.S. state of Maryland. The state highway runs 16.81 miles (27.05 km) from MD 45 in Towson north to MD 23 near Jarrettsville. MD 146 connects Towson with Loch Raven Reservoir, an impoundment of Gunpowder Falls. The state highway also serves the northern Baltimore County community of Jacksonville and Jarrettsville in western Harford County. MD 146 was constructed as two different state highways on either side of Loch Raven Reservoir. The section of the state highway in Towson was built in the 1910s and the portion through Jacksonville to Jarrettsville was constructed in the late 1920s and early 1930s. The gap in MD 146 through Loch Raven Reservoir was filled in two steps of maintenance swaps in the early 1960s and late 1970s.

Maryland Route 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 in Hickory north and west to the Pennsylvania state line near Norrisville, where the highway continues as Pennsylvania Route 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.