Harford County maintains approximately 1043.58 miles of roadway. Harford County DOES NOT maintain private roads (indicated with blue street name signs), roads within the incorporated municipalities (Town of Bel Air, City of Havre de Grace, and City of Aberdeen) or federal or state roads. The Maryland State Highway Administration maintains the state roads in Harford County. State roads are numbered routes. For example, Maryland Route 543 or Fountain Green Road is a state road. The Maryland Transportation Authority maintains the roads in Harford County on Interstate 95.

Harford County maintains its roads for use by residents, travelers, farmers and businesses. Under the Pavement Management Program, asphalt roadways are assessed annually for necessary maintenance. Dirt and gravel roadways are maintained on a regular or as-needed basis. Most of the maintenance is performed by Harford County Highway Maintenance. In addition to repairs to the driving surface, that maintenance includes right-of-way mowing, snow plowing, and shoulder pulling.

Harford County Maintained Roads EXCLUDE private roads,
roads within the municipalities (shown in dark green),
state roads (numbered routes - shown in red),
and I-95 (also shown in red)