In Falmouth, Route 28 turns north and continues through the western part of Plymouth County and the eastern part of Norfolk County; it then passes through downtown Boston before heading north via Lawrence to the New Hampshire state line, where it continues as New Hampshire Route 28.

Except for an extension into Cape Cod in 1926, the overall highway layout and routing is largely unchanged from its original design.

Roughly half of the McGrath Highway is an elevated freeway through East Somerville, while being supplemented by at-grade frontage roads.

Many of the roads leading from Boston to the surrounding towns were first laid out as privately owned and operated turnpikes at the beginning of the 19th century.

One of the roads used by modern Route 28 leading from the northern suburbs of Boston in the direction of Manchester, New Hampshire was the Andover and Medford Turnpike.

The turnpike corporation was chartered in June 1805 and had authority to build from the marketplace in Medford to a point in the town of Andover.

An act by the General Court in February 1807 allowed the Andover and Medford company to maintain a toll gate at the Essex-Middlesex county line jointly with the Essex Turnpike corporation.

The road cost approximately $78,300 to build the eight miles from Randolph Center to Milton Lower Mills in 1805.

In 1815, the Blue Hills Turnpike company was allowed to impose a fine on any persons who tried to avoid paying the tolls.

The triple-concurrency of Routes 1, 6, and 28 continued through the Emerald Necklace following the Jamaicaway, the Riverway, and a short section of Boylston Street to Charlesgate, and then crossed the Charles River using the Harvard Bridge.

The road from Bourne to Orleans along the south shore of the Cape was the easternmost section of New England Route 3.

The major exceptions are in Boston, where some of the original routing was changed over the years, and on the Cape, where a freeway section between Falmouth and Bourne was completed in the mid-1960s.

From the Boston University Bridge, the two routes used Memorial Drive and Cambridge Parkway to reach the Northern Artery.

Just beyond the Franklin Zoo, C28 turned west along Seaver Street, continuing through Roxbury along Columbus Avenue.

Route 28 was also later shifted to use its modern alignment along Embankment Road and the Charles River Dam Bridge.

The McCarthy Overpass, which carries Route 28 as McGrath Highway through part of Somerville, was built in the early 1950s, before Interstate 93.

[2] The parallel Northern Expressway segment connecting Medford (where I-93 ended in 1963) and the Central Artery was constructed between 1965 and 1973.

As the McCarthy Overpass reached the end of its expected life, the Massachusetts Department of Transportation announced in 2013 the preferred replacement was a ground-level boulevard.

[3] The project is expected to cost $100 million and is programmed with state and federal money for 2027-2030; as of 2024, work on producing the 25% design was underway.

Between 1941 and 1943, the road south of the Bourne Bridge was widened to a four-lane, divided highway to the Pocasset Rotary and renamed General MacArthur Boulevard.

The highway was part of Route 28 until paralleling General MacArthur Boulevard expressway opened to traffic in 1961.