MD 30 originated in the colonial era as part of a wagon road connecting the fledgling port of Baltimore with the new settlement that was to become Hanover.

The Hampstead Bypass was planned as early as the 1960s to ameliorate the increasing congestion along the MD 30 corridor that was only exacerbated when Interstate 795 (I-795) was completed to Reisterstown in the late 1980s.

As the highway leaves Reisterstown, Old Hanover Pike splits to the northeast and MD 30 crosses over the Maryland Midland Railway.

At the hamlet of Woodensburg, the old road splits northeast again to follow the railroad through the village of Boring.

The state highway, once again named Hanover Pike, has a short four-lane divided section through a commercial area before reducing to a two-lane undivided road.

The highway continues as PA 94 (Baltimore Pike) through southwestern York County to Hanover.

[1][4] The first road along the corridor of MD 30 was a wagon road cut along an existing Indian trail in 1736 and 1737 to connect the Conewago Settlement, which later became Hanover, with Baltimore Town, which served as a much closer port for farmers and merchants in York County and Adams County, Pennsylvania, than Philadelphia.

The present bridge over the railroad was completed in 1936, but the relocated highway, which replaced what is now Old Hanover Road to the east, was not placed under construction until 1938 and did not open until 1939.

[5][11][12] MD 30 was widened from Hampstead south to the Baltimore–Carroll county line in 1938 with a pair of 3-foot (0.91 m)-wide macadam shoulders, expanding the road's width to 21 feet (6.4 m).

In 1991, heavy groundwater contamination by industrial chemicals was discovered near the southern end of the proposed route, then 5.8 miles (9.3 km) long, at a Black & Decker factory and near the northern end of the planned route at a shopping center.

[24] In 1998, the route of the Hampstead Bypass changed a third time when the bog turtle habitat was found to be larger than previously discovered.

Local sentiment was that the county was relatively neglected and did not get its fair share of state highway funding for close to 40 years.

[15] By 1997, the start of construction of the Hampstead Bypass was proposed for three to four years in the future; at that time, most of the engineering phase was complete but most of the highway right-of-way had yet to be purchased.

The business route begins at a four-leg roundabout with MD 30, which heads south as Hanover Pike and northwest as the Hampstead Bypass, and Phillips Drive.

MD 30 Business parallels CSX's Hanover Subdivision through an industrial area that contains the headquarters of JoS.

The highway's name changes from Hanover Pike to Main Street as it enters the town of Hampstead at an oblique grade crossing of the railroad.

In the community of Greenmount, the railroad veers away to the northeast and MD 30 Business veers northwest to its northern terminus at a three-leg roundabout with MD 30, which heads southwest as the Hampstead Bypass and north as Hanover Pike toward Manchester.

[32] Now that MD 30 has bypassed Hampstead, a streetscape project is planned to rebuild Main Street through town starting in 2014 or 2015.