[4] The United States Census Bureau defines an urban area in northeast Maryland in which Bel Air is the principal settlement: the Bel Air–Aberdeen, MD urban area had a population of 214,647 as of the 2020 census, making it the 180th most-populous in the United States.

Four years later, the town had expanded as local politicians, merchants, and innkeepers purchased lots from Scott, and the county commissioners decided to change its name to the more appealing "Belle Aire."

In 1782, just two years after its founding, it became Harford's county seat, and Daniel Scott (Aquilla's son) started building a courthouse on Main Street.

The introduction of the canning industry, the Ma & Pa railroad and related financial businesses jump started the growth after the Civil War.

Today, Bel Air is the center for governmental, educational, cultural, medical, and commercial institutions in the county.

In 1972, another fire struck, decimating the east side of Main Street and causing $2 million in damage.

In 1970, H. Rap Brown, a member of the Black Panthers and the fourth chairman of the Student Nonviolent Coordinating Committee (SNCC), was charged with instigating a riot after a rally in Cambridge, Maryland; a change in venue brought his trial to Bel Air.

Two black militants drove to Bel Air in a truck laden with plastic explosives, intending to attack the courthouse.

[5] Into the 1950s, the town hosted horse racing at Bel Air Racetrack, which stood where the Harford Mall is today.

Bel Air features hot, often humid summers, mild, wet springs, pleasant falls and cool to chilly winters.

The primary means of transportation to and from Bel Air is by road, and the most prominent highway serving the town is Maryland Route 24.

US 1 formerly ran through the town, but now follows a bypass around the northwest side, with U.S. Route 1 Business following US 1's former alignment through Bel Air.

The three small plane airports in the metropolitan area are: In the mid 20th century the Maryland and Pennsylvania Railroad ("Ma and Pa") ran through town, but the tracks were dismantled in 1958.

The station was located (at milepost 26.5) on Rockspring Ave. between Broadway and Ellendale St. Much of the railroad's former route in and around Bel Air is now the Ma and Pa walking trail, which cuts through various wooded sections of town in and around Heavenly Waters Park.

The service operates 7 routes throughout the county, including the Orange Line, or the Bel Air Circulator.

Overseeing the department is Charles Moore, lifelong Harford County resident and former Maryland State Police captain.

[12] The Aegis is the main daily print news publication for Bel Air and surrounding Harford County.

The chair of the Board, elected by its members each year, is given the ceremonial title of Mayor of Bel Air.