Maryland Route 273 (MD 273) is a state highway in the U.S. state of Maryland. Known for most of its length as Telegraph Road, the highway runs 16.58 miles (26.68 km) from U.S. Route 1 (US 1) near Harrisville east to the Delaware state line near Appleton, where the highway continues east as Delaware Route 273 (DE 273). MD 273 is the main east–west highway of northern Cecil County, connecting Conowingo (via US 1), Port Deposit (via MD 276), and Rising Sun with Newark, Delaware, via the communities of Calvert and Fair Hill, where the highway intersects MD 272 and MD 213, respectively. The state highway also provides access to the Fair Hill Training Center and the Fair Hill Natural Resources Management Area.

MD 273 west of Fair Hill was constructed as one of the original state roads starting in the early 1910s. MD 273 west of and through Rising Sun was the original course of US 1, which was paved from the Susquehanna River to northeast of Rising Sun in the 1910s. The state highway east of Rising Sun was paved in several sections between the mid-1910s and the late 1920s. The portion of original US 1 west of Octoraro Creek comprised a western segment of MD 273 from the late 1920s to the late 1950s. The section of US 1 that followed present-day MD 273 was reconstructed in the early to mid-1950s, shortly before MD 273 was extended west to its present western terminus when US 1 was placed on the Rising Sun Bypass in the late 1950s. The highway was reconstructed from east of Rising Sun to the Delaware state line in several stages from the late 1950s to the early 1970s.