MD 543 begins at an intersection with US 40 (Pulaski Highway) in an industrial area of Riverside.
 The state highway initially heads southeast from US 40, then curves clockwise 180 degrees toward the northwest to cross over US 40 and CSX's Philadelphia Subdivision railroad line.
 MD 543 heads northwest as Riverside Parkway, a partially controlled-access two-lane highway between residential subdivisions.
 The state highway expands to a four-lane divided highway immediately before Church Creek Road and enters a commercial area.
 After intersecting MD 7 (Philadelphia Road), MD 543's name changes to Creswell Road and the highway meets I-95 (John F. Kennedy Memorial Highway) at a diamond interchange.
 The state highway reduces to a two-lane road at its intersection with county-maintained Creswell Road.

MD 543 continues northwest and traverses James Run within the Harford Furnace Historic District.
 The state highway passes the historic homes Fair Meadows and Best Endeavor in the rural community of Creswell.
 After intersecting MD 136 (Calvary Road), MD 543 continues northwest as Fountain Green Road, which crosses over a branch of Bynum Run and passes the historic homes Mount Adams and Broom's Bloom.
 The state highway expands to a three-lane road with center turn lane as the highway becomes lined with residential subdivisions in the suburban community of Fountain Green.
 MD 543 reduces to two lanes after intersecting MD 22 (Churchville Road) in the center of the community.
 The state highway continues northwest through a mix of residential subdivisions, farmland, and forest on the way to Hickory, where MD 543 intersects US 1 (Hickory Bypass) and US 1 Business (Conowingo Road) in rapid succession.

MD 543 continues north as Ady Road into rural areas.
 Just before crossing Deer Creek, the state highway intersects Walters Mill Road, which provides access to the historic D. H. Springhouse.
 MD 543 continues north and intersects MD 440 (Dublin Road) and MD 646 (Prospect Road) in the hamlets of Ady and Emory Church, respectively.
 MD 543 parallels Broad Creek and intersects Highland Road, which heads west from the state highway to serve the village of Street, as the highway continues northwest to Pylesville.
 In Pylesville, the state highway intersects Old Pylesville Road, with a park and ride lot located west of the intersection, and crosses a tributary of Broad Creek before reaching its northern terminus at MD 165 (Pylesville Road).
MD 543 begins at an intersection with US 40 (Pulaski Highway) in an industrial area of Riverside.  The state highway initially heads southeast from US 40, then curves clockwise 180 degrees toward the northwest to cross over US 40 and CSX's Philadelphia Subdivision railroad line.  MD 543 heads northwest as Riverside Parkway, a partially controlled-access two-lane highway between residential subdivisions.  The state highway expands to a four-lane divided highway immediately before Church Creek Road and enters a commercial area.  After intersecting MD 7 (Philadelphia Road), MD 543's name changes to Creswell Road and the highway meets I-95 (John F. Kennedy Memorial Highway) at a diamond interchange.  The state highway reduces to a two-lane road at its intersection with county-maintained Creswell Road.
MD 543 continues northwest and traverses James Run within the Harford Furnace Historic District.  The state highway passes the historic homes Fair Meadows and Best Endeavor in the rural community of Creswell.  After intersecting MD 136 (Calvary Road), MD 543 continues northwest as Fountain Green Road, which crosses over a branch of Bynum Run and passes the historic homes Mount Adams and Broom's Bloom.  The state highway expands to a three-lane road with center turn lane as the highway becomes lined with residential subdivisions in the suburban community of Fountain Green.  MD 543 reduces to two lanes after intersecting MD 22 (Churchville Road) in the center of the community.  The state highway continues northwest through a mix of residential subdivisions, farmland, and forest on the way to Hickory, where MD 543 intersects US 1 (Hickory Bypass) and US 1 Business (Conowingo Road) in rapid succession.
MD 543 continues north as Ady Road into rural areas.  Just before crossing Deer Creek, the state highway intersects Walters Mill Road, which provides access to the historic D. H. Springhouse.  MD 543 continues north and intersects MD 440 (Dublin Road) and MD 646 (Prospect Road) in the hamlets of Ady and Emory Church, respectively.  MD 543 parallels Broad Creek and intersects Highland Road, which heads west from the state highway to serve the village of Street, as the highway continues northwest to Pylesville.  In Pylesville, the state highway intersects Old Pylesville Road, with a park and ride lot located west of the intersection, and crosses a tributary of Broad Creek before reaching its northern terminus at MD 165 (Pylesville Road).
Maryland Route 543