Combining the 2 major sections (and a "silent" concurrency with US 6 through Eastham, Wellfleet, and South Truro), the highway is approximately 62 miles (100 km) long.

From there, it goes thus: Since 1982, Route 6A has ended at an intersection (signalized until 2010) with US 6 at Herring Cove, part of the Cape Cod National Seashore.

[citation needed] Some maps erroneously had the northern Route 6A having its southern terminus at US 6 along Mayflower Avenue in Provincetown.

[citation needed] A second stretch in 1954 was signed when a US 6 bypass was constructed in Truro and Provincetown, although in Provincetown, Route 6A was signed along Bradford Street instead of US 6's former routing on Commercial Street, as the latter road had become one-way westbound.

[citation needed] A third stretch in 1956 was signed between Route 132 in Barnstable and the Orleans–Eastham town line when the US 6 freeway was completed.

[citation needed] Route 6A does not officially exist in Eastham or Wellfleet as the road is in an unsigned concurrency with US 6.