MD 135 begins at an intersection with US 219 on the eastern edge of Oakland.
 Northbound US 219 (Oak Street) continues straight west into downtown Oakland, southbound US 219 (Garrett Highway) heads south toward Red House, and 9th Street (unsigned MD 219) heads north along the alignment of the future Oakland Bypass.
 MD 135 heads east through Mountain Lake Park as Maryland Highway, a controlled access two-lane undivided highway.
 Oakland Drive, which is unsigned MD 825B, splits to the northeast to serve residential areas on the north side of town.
 The old alignment rejoins MD 135 at G Street before access controls cease upon crossing the Little Youghiogheny River.
 The state highway intersects MD 560 (Paull Street), which heads south into Loch Lynn Heights.
 After crossing the river again, MD 135 leaves Mountain Lake Park.
 The state highway passes scattered residences, farms, and businesses before entering Deer Park.
 After passing Deer Park Hotel Road, which passes the Pennington Cottage, MD 135 intersects the old alignment of MD 38, which is Sand Flat Road to the north and Main Street to the south.
 The state highway passes the historic home Glamorgan and Edgewood Drive, part of the old alignment of MD 38, before leaving Deer Park.
 Upon reaching the hamlet of Altamont, MD 495 (Swanton Road) continues straight northeast toward Swanton while MD 135 turns to the southeast.

MD 135 heads straight southeast toward a grade-separated crossing of CSX's Mountain Subdivision very close to the railroad's crossing of the Eastern Continental Divide.
 The state highway curves to the northeast and gently ascends Backbone Mountain.
 A scenic overlook marks the highest point on MD 135 (2,969 feet (905 m)) shortly before the intersection with MD 38 (Kitzmiller Road).
The state highway continues northeast along the ridgeline through Potomac-Garrett State Forest and intersects Swanton Road and a few roads on the south side of the highway that access Jennings Randolph Lake.
 Upon leaving the state forest, MD 135 begins to pass scattered residences ahead of the descent of Backbone Mountain, which has grades as steep as 9%.
 Trucks are required to stop at three different brake check locations and obey a posted speed limit of 10 mph (16 km/h).
 After Bloomington Hill Road splits to the north and the state highway passes the third brake check stop, a runaway truck ramp splits to the south.
 The downhill grade eases as MD 135 enters Bloomington, where the name of the highway changes to Bloomington Road.
 After passing through residential areas, the state highway crosses the Mountain Subdivision and the Savage River before meeting Savage Hillside Road at a T intersection in front of Franklin Hill.

MD 135 turns southeast into Allegany County and enters the town of Luke as Pratt Street.
 The state highway immediately intersects Masteller Road, which is unsigned MD 135D and meets the eastern end of the western segment of West Virginia Route 46 (WV 46) at the North Branch Potomac River.
 At a bend in the river, MD 135 makes a sharp turn to the north around the mountain and the road passes the large NewPage Corporation paper mill.
 The state highway turns east and its name changes to Church Street upon entering Westernport, where the highway intersects MD 36 (New Georges Creek Road), which crosses the North Branch Potomac River to become the eastern segment of WV 46.
 MD 135 crosses Georges Creek and meets the Georges Creek Railway at-grade before intersecting Main Street, which is unsigned MD 937.
 Upon leaving Westernport, the road's name changes to McCoole–Westernport Road.
 MD 135 parallels the North Branch Potomac River and Georges Creek Railway as it passes scattered residences and businesses.
 Upon reaching McCoole, the highway passes unsigned MD 135A, which provides an alternate access route to US 220 north.
 Shortly after, MD 135 reaches Paxton Street, which is officially MD 135B but is marked as MD 135.
Paxton Street leads to a junction with US 220 (McMullen Highway).
 MD 135 itself continues east under the McCoole–Keyser bridge to its eas
MD 135 begins at an intersection with US 219 on the eastern edge of Oakland.  Northbound US 219 (Oak Street) continues straight west into downtown Oakland, southbound US 219 (Garrett Highway) heads south toward Red House, and 9th Street (unsigned MD 219) heads north along the alignment of the future Oakland Bypass.  MD 135 heads east through Mountain Lake Park as Maryland Highway, a controlled access two-lane undivided highway.  Oakland Drive, which is unsigned MD 825B, splits to the northeast to serve residential areas on the north side of town.  The old alignment rejoins MD 135 at G Street before access controls cease upon crossing the Little Youghiogheny River.  The state highway intersects MD 560 (Paull Street), which heads south into Loch Lynn Heights.  After crossing the river again, MD 135 leaves Mountain Lake Park.  The state highway passes scattered residences, farms, and businesses before entering Deer Park.  After passing Deer Park Hotel Road, which passes the Pennington Cottage, MD 135 intersects the old alignment of MD 38, which is Sand Flat Road to the north and Main Street to the south.  The state highway passes the historic home Glamorgan and Edgewood Drive, part of the old alignment of MD 38, before leaving Deer Park.  Upon reaching the hamlet of Altamont, MD 495 (Swanton Road) continues straight northeast toward Swanton while MD 135 turns to the southeast.
MD 135 heads straight southeast toward a grade-separated crossing of CSX's Mountain Subdivision very close to the railroad's crossing of the Eastern Continental Divide.  The state highway curves to the northeast and gently ascends Backbone Mountain.  A scenic overlook marks the highest point on MD 135 (2,969 feet (905 m)) shortly before the intersection with MD 38 (Kitzmiller Road). The state highway continues northeast along the ridgeline through Potomac-Garrett State Forest and intersects Swanton Road and a few roads on the south side of the highway that access Jennings Randolph Lake.  Upon leaving the state forest, MD 135 begins to pass scattered residences ahead of the descent of Backbone Mountain, which has grades as steep as 9%.  Trucks are required to stop at three different brake check locations and obey a posted speed limit of 10 mph (16 km/h).  After Bloomington Hill Road splits to the north and the state highway passes the third brake check stop, a runaway truck ramp splits to the south.  The downhill grade eases as MD 135 enters Bloomington, where the name of the highway changes to Bloomington Road.  After passing through residential areas, the state highway crosses the Mountain Subdivision and the Savage River before meeting Savage Hillside Road at a T intersection in front of Franklin Hill.
MD 135 turns southeast into Allegany County and enters the town of Luke as Pratt Street.  The state highway immediately intersects Masteller Road, which is unsigned MD 135D and meets the eastern end of the western segment of West Virginia Route 46 (WV 46) at the North Branch Potomac River.  At a bend in the river, MD 135 makes a sharp turn to the north around the mountain and the road passes the large NewPage Corporation paper mill.  The state highway turns east and its name changes to Church Street upon entering Westernport, where the highway intersects MD 36 (New Georges Creek Road), which crosses the North Branch Potomac River to become the eastern segment of WV 46.  MD 135 crosses Georges Creek and meets the Georges Creek Railway at-grade before intersecting Main Street, which is unsigned MD 937.  Upon leaving Westernport, the road's name changes to McCoole–Westernport Road.  MD 135 parallels the North Branch Potomac River and Georges Creek Railway as it passes scattered residences and businesses.  Upon reaching McCoole, the highway passes unsigned MD 135A, which provides an alternate access route to US 220 north.  Shortly after, MD 135 reaches Paxton Street, which is officially MD 135B but is marked as MD 135. Paxton Street leads to a junction with US 220 (McMullen Highway).  MD 135 itself continues east under the McCoole–Keyser bridge to its eas
Maryland Route 135