MD 45 begins at an intersection with US 1/US 40 Truck (North Avenue) at the northwest corner of
Green Mount Cemetery in Baltimore. Greenmount Avenue continues south as a city street to Forrest Street and Monument Street east of
Downtown Baltimore. MD 45 heads north as a four-lane undivided street between the
Barclay and
East Baltimore Midway neighborhoods and crosses over
CSX's
Baltimore Terminal Subdivision railroad line. The state highway continues north through
Waverly, where the street passes
St. John's Episcopal Church and intersects 33rd Street. MD 45 is paralleled to the east by Old York Road through Waverly and
Pen Lucy. At 43rd Street, MD 45's name changes to York Road. The name change occurs where the highway exited the city limits of Baltimore between 1888 and 1917. MD 45 continues north as a five-lane road with a
center left-turn lane. Between
Cold Spring Lane and
Northern Parkway, the state highway passes through
Mid-Govans, which is home to the
Senator Theater and loses the center left-turn lane. MD 45 leaves the city limits and passes through the Baltimore County community of
Rodgers Forge. The state highway passes along the eastern margin of
Towson University before reaching the southern edge of downtown Towson, where
MD 45 Bypass splits to the northwest along Burke Avenue. In the center of the county seat adjacent to the
Towson Town Center shopping mall, MD 45 passes through the racetrack-shaped Towson Roundabout, where the state highway meets the southern end of
MD 146 (Dulaney Valley Road) and east–west
Joppa Road. On either side of the
roundabout, the state highway narrows to two lanes for on-street parking. MD 45 heads northwest from the roundabout, becoming four lanes again, and meets the northern end of MD 45 Bypass (Bosley Avenue) before it gains a center left-turn lane and passes east of the
George Washington Carver Center for Arts and Technology. The route has a
partial cloverleaf interchange with I-695 (Baltimore Beltway), at which point it is a four-lane
divided highway. The state highway continues north through the densely populated suburban area of Lutherville as a five-lane road with a center left-turn lane, where the highway intersects Seminary Road, which heads west as
MD 131. The west side of MD 45 is lined with commercial and industrial parks as it passes through Timonium. Between Timonium Road and Padonia Road, both of which head west to interchanges with I-83, the state highway passes along the eastern edge of the
Timonium Fairgrounds, home of the
Maryland State Fair and the Baltimore County 4-H Fair. The industrial parks continue past Warren Road in Cockeysville, where the highway crosses Beaver Dam Run. MD 45 meets the western end of
MD 145 (Ashland Road) before arriving in Hunt Valley, where the highway intersects Shawan Road at
Hunt Valley Town Center, a residential and retail center. North of Shawan Road, MD 45 becomes a two-lane undivided road that crosses Western Run and curves northeast before resuming its northward course through the community of Sparks, where the highway has an intersection with Belfast Road and passes several industrial parks. The state highway continues through the village of Hereford, which contains the western terminus of
MD 138 (Monkton Road) and the eastern terminus of
MD 137 (Mount Carmel Road) one block apart. North of Hereford, MD 45 passes west of
Hereford High School and descends into the valley of
Gunpowder Falls, where the highway closely parallels I-83. The two highways separate, with the state highway passing by the
Half-Way House, a preserved toll house from the 19th-century turnpike that is halfway between Baltimore and York. In Parkton, MD 45 intersects Middletown Road and passes over the
Torrey C. Brown Rail Trail and Little Gunpowder Falls. North of the village, the state highway crosses to the west side of I-83 at a
diamond interchange with the Interstate. The state highway intersects
MD 439 (Old York Road) and Freeland Road in the community of Maryland Line before reaching its northern terminus at the Pennsylvania state line. The roadway continues north as SR 3001 (
Susquehanna Trail), an unsigned
quadrant route, toward the borough of
Shrewsbury. MD 45 is a part of the
National Highway System as a principal arterial from US 1 in Baltimore to Shawan Road in Hunt Valley except for the short stretch between MD 146 and the northern junction with MD 45 Bypass in Towson. ==History==