MD 17 begins at the Virginia state line at the Potomac River in the city of Brunswick.
 The roadway continues into Loudoun County, Virginia as SR 287 (Berlin Pike), which heads south toward Lovettsville.
 MD 17 crosses the river on the Brunswick Bridge, a two-lane steel girder bridge that also passes over the Chesapeake and Ohio Canal, CSX's Metropolitan Subdivision, Walnut Street, Virginia Avenue, and Potomac Street.
 The bridge's northern end lands just south of a roundabout that connects MD 17 with Petersville Road, Maryland Avenue, and both directions of B Street.
 Petersville Road, the old alignment of MD 17, heads south into the Brunswick Historic District and becomes Maple Avenue, which provides access to Chesapeake and Ohio Canal National Historical Park and the historic Brunswick train station, which is served by MARC's Brunswick Line.

MD 17 heads north from the Brunswick Roundabout as two-lane undivided Petersville Road, which climbs out of the narrow Potomac River valley.
 At the top of the hill, the state highway leaves the city of Brunswick and enters the village of Rosemont, where the highway intersects MD 79 and MD 464 (Souder Road).
 Petersville Road continues north as MD 79 while MD 17 turns northwest onto Burkittsville Road.
 The state highway leaves the village of Rosemont, passes through a roundabout intersection with Volunteer Drive and intersects the western end of Rosemont Drive through a roundabout, the old alignment of MD 17 that is unsigned MD 871G. That roundabout also intersects the main entrance to the Brunswick Crossing development started in the early 2000s.
MD 17 continues on to intersect MD 180 (Jefferson Pike) at a roundabout before crossing over US 340 (Jefferson National Pike) at a diamond interchange.
 At the end of the overpass, MD 17 passes through another roundabout which serves to distribute traffic to and from the on and off ramps of westbound US 340.
North of US 340, the state highway runs mostly straight through farmland parallel to the upper reaches of Little Catoctin Creek intersecting with Brentland Rd.
and then Lee's Lane following which the highway passes through a pair of right-angle curves and parallels South Mountain to the hamlet of Coatsville.

MD 17 curves to the northeast and enters the town of Burkittsville, where the highway's name becomes Potomac Street.
 Within the Burkittsville Historic District, the state highway intersects Main Street, which heads west to Crampton's Gap, a low point in South Mountain that contains Gathland State Park.
 MD 17 leaves Burkittsville and crosses Broad Run near the hamlet of Arnoldtown, then meets the northern end of MD 383 (Broad Run Road) and the west end of Bennies Hill Road, which leads to the Bennies Hill Road Bridge and historic Shafer's Mill.
 The state highway continues across Middle Creek and parallels Catoctin Creek before crossing the latter stream on a through truss bridge.
 MD 17 enters the town of Middletown just south of its intersection with Jefferson Street and Old Middletown Road.
 The state highway passes through town as Church Street and meets US 40 Alternate Business (Main Street) in the center of the Middletown Historic District.

MD 17 leaves Middletown as Myersville Middletown Road, which heads northeast then curves northwest to parallel I-70 (Eisenhower Memorial Highway).
 The two highways cross Little Catoctin Creek—this creek being a tributary of Catoctin Creek rather than the Potomac River-feeding creek near Brunswick—near the state highway's intersection with Harmony Road, then MD 17 veers west away from the Interstate.
 The state highway intersects Old Hagerstown Road at an oblique angle and crosses Catoctin Creek again before veering north and reaching Ventrie Court, which heads east to provide access to a park and ride lot serving MTA Maryland commuter buses.
The road temporarily expands to a four-lane divided highway for its diamond interchange with I-70 at the town limit of Myersville.
 After reducing to two lanes, MD 17 continues as Main Street toward the center of town, where the state highway turn
MD 17 begins at the Virginia state line at the Potomac River in the city of Brunswick.  The roadway continues into Loudoun County, Virginia as SR 287 (Berlin Pike), which heads south toward Lovettsville.  MD 17 crosses the river on the Brunswick Bridge, a two-lane steel girder bridge that also passes over the Chesapeake and Ohio Canal, CSX's Metropolitan Subdivision, Walnut Street, Virginia Avenue, and Potomac Street.  The bridge's northern end lands just south of a roundabout that connects MD 17 with Petersville Road, Maryland Avenue, and both directions of B Street.  Petersville Road, the old alignment of MD 17, heads south into the Brunswick Historic District and becomes Maple Avenue, which provides access to Chesapeake and Ohio Canal National Historical Park and the historic Brunswick train station, which is served by MARC's Brunswick Line.
MD 17 heads north from the Brunswick Roundabout as two-lane undivided Petersville Road, which climbs out of the narrow Potomac River valley.  At the top of the hill, the state highway leaves the city of Brunswick and enters the village of Rosemont, where the highway intersects MD 79 and MD 464 (Souder Road).  Petersville Road continues north as MD 79 while MD 17 turns northwest onto Burkittsville Road.  The state highway leaves the village of Rosemont, passes through a roundabout intersection with Volunteer Drive and intersects the western end of Rosemont Drive through a roundabout, the old alignment of MD 17 that is unsigned MD 871G. That roundabout also intersects the main entrance to the Brunswick Crossing development started in the early 2000s. MD 17 continues on to intersect MD 180 (Jefferson Pike) at a roundabout before crossing over US 340 (Jefferson National Pike) at a diamond interchange.  At the end of the overpass, MD 17 passes through another roundabout which serves to distribute traffic to and from the on and off ramps of westbound US 340. North of US 340, the state highway runs mostly straight through farmland parallel to the upper reaches of Little Catoctin Creek intersecting with Brentland Rd. and then Lee's Lane following which the highway passes through a pair of right-angle curves and parallels South Mountain to the hamlet of Coatsville.
MD 17 curves to the northeast and enters the town of Burkittsville, where the highway's name becomes Potomac Street.  Within the Burkittsville Historic District, the state highway intersects Main Street, which heads west to Crampton's Gap, a low point in South Mountain that contains Gathland State Park.  MD 17 leaves Burkittsville and crosses Broad Run near the hamlet of Arnoldtown, then meets the northern end of MD 383 (Broad Run Road) and the west end of Bennies Hill Road, which leads to the Bennies Hill Road Bridge and historic Shafer's Mill.  The state highway continues across Middle Creek and parallels Catoctin Creek before crossing the latter stream on a through truss bridge.  MD 17 enters the town of Middletown just south of its intersection with Jefferson Street and Old Middletown Road.  The state highway passes through town as Church Street and meets US 40 Alternate Business (Main Street) in the center of the Middletown Historic District.
MD 17 leaves Middletown as Myersville Middletown Road, which heads northeast then curves northwest to parallel I-70 (Eisenhower Memorial Highway).  The two highways cross Little Catoctin Creek—this creek being a tributary of Catoctin Creek rather than the Potomac River-feeding creek near Brunswick—near the state highway's intersection with Harmony Road, then MD 17 veers west away from the Interstate.  The state highway intersects Old Hagerstown Road at an oblique angle and crosses Catoctin Creek again before veering north and reaching Ventrie Court, which heads east to provide access to a park and ride lot serving MTA Maryland commuter buses. The road temporarily expands to a four-lane divided highway for its diamond interchange with I-70 at the town limit of Myersville.  After reducing to two lanes, MD 17 continues as Main Street toward the center of town, where the state highway turn
Maryland Route 17