Maryland Route 28 is a state highway in the U.S. state of Maryland. The state highway runs 37.38 miles (60.16 km) from U.S. Route 15 in Point of Rocks east to MD 182 in Norwood. The western portion of MD 28 is a rural highway connecting several villages in southern Frederick County and western Montgomery County. By contrast, the eastern portion of the state highway is a major east–west commuter route, particularly within Gaithersburg and Rockville.

U.S. Route 15 (US 15) is a part of the United States Numbered Highway System that runs from Walterboro, South Carolina, north to Painted Post, New York. In Maryland, the highway runs 37.85 miles (60.91 km) from the Virginia state line at the Potomac River in Point of Rocks north to the Pennsylvania state line near Emmitsburg. Known for most of its length as Catoctin Mountain Highway, US 15 is the primary north–south highway of Frederick County. The highway connects the county seat of Frederick with Point of Rocks, Leesburg, Virginia, and Charles Town, West Virginia, to the south and with Thurmont, Emmitsburg, and Gettysburg, Pennsylvania, to the north. US 15 is an expressway throughout the state except for the portion south of MD 28. The highway is a freeway along its concurrency with US 340 and through Frederick, where the highway meets US 40 and Interstate 70 (I-70). US 15 has a business route through Emmitsburg.