At Point of Rocks (MP 64.7), where the speed limit is 30 mph, the Old Main Line diverges to the east-northeast and the main line turns southeast, with the brick depot in the apex between the diverging lines. There's a single-track east leg of the wye, passing east of the depot, with a dirt road grade crossing on it. The Old Main Line has Two Main Tracks, CTC, maximum speed 45 mph, and heads northeast, past the start of single track (40 mph on the switch), CTC, at Doub (MP 62.0), Adamstown, Loyer (MP 59.0), Buckeystown, where it turns north-northeast, and Lime Kiln (MP 56.8), turning east, past the wye on the north side with the Frederick Industrial Track, at Frederick Junction (MP 54.2), a 35 mph speed restriction, from MP 54.2 to MP 51.2, the 11,950 ft. north side siding, from West Reel (MP 53.8) to East Reel (MP 51.4), a 25 mph speed restriction, from MP 51.2 to MP 48.9, Ijamsville (MP 49.6), a 30 mph speed restriction, from MP 48.9 to MP 47.9, Monrovia, a 35 mph speed restriction, from MP 47.9 to MP 32.0, and Bartholomew.
There is a 10,750 ft. north-side siding, from West Plane (MP 43.2) to East Plane (MP 41.1), where the Mt. Airy Industrial Track departs on the north side, a detector at "Ridgeville" (MP 38.9), Twin Arch (MP 38.8), the Mt. Airy Tunnel, a turn east-northeast, Watersville Junction, where the erstwhile continuation of today's Mt. Airy Industrial Track once trailed in on the north side, a turn east-southeast, Woodbine (MP 34.2), a turn curvily east, the 8,352 ft. north side siding, from West Hood (MP 33.1), past a 30 mph speed restriction from MP 32.0 to MP 30.1, to East Hood (MP 31.5), Gaither, a 25 mph speed restriction, from MP 30.1 to MP 12.7, Sykesville (MP 28.8), Gorsuch, Harington, and Marriottsville, where the line turns south, east past Woodstock, and just west of due south.
The line turns east, past the 9,200 ft. north-side siding, from West Davis (MP 21.9) to East Davis (MP 20.0) and a detector at "Daniels" (MP 18.1), southeast, south to Ellicott City (MP 12.8), east, bridging over the Patapsco River, and curvily southeast, along the Patapsco River valley, with a 30 mph speed restriction, from MP 12.7 to MP 7.4, past Ilchester, Ilchester Tunnel, Orange Grove, and the 9,621 ft. south-side siding, from West Avalon (MP 9.8) to East Avalon (MP 7.9), turning east at Relay (MP 7.4), where the Capital subdivision trails in from the southwest, on the south side.