North of Portland, the highway bridges the Presumpscot River (via the Martin's Point Bridge) in Falmouth, the Royal River in Yarmouth, and the Cousins River in Freeport before following the Androscoggin River through Brunswick and crossing the Kennebec River on the Sagadahoc Bridge between Bath and Woolwich. The section between Brunswick (at its junction with US 201) and Bath is a four-lane freeway, and the route continues as a four-lane expressway through most of Bath, then crosses on a two-lane viaduct before becoming four lanes again on the bridge over the Kennebec River. It then becomes a three-lane road (with center turning lane) through Woolwich and then reverts to two lanes after that as it continues north toward Wiscasset.
In Rockland, there is a bypass of downtown (US 1A) which travels along Broadway and Maverick streets, while US 1 itself has a one way pair with Main and Union streets in the downtown Rockland area (Main Street traffic goes north with two lanes, while Union Street traffic is southbound).
US 1 south of Calais was initially part of the Atlantic Highway and became Route 1 when the New England road marking system was established in 1922.[4] The northward continuation from Calais was later designated as part of Route 24. In the original plan, Route 24 was to run from Brunswick to Moosehead Lake in Greenville. By 1925, however, Maine had transferred the Route 24 designation to a completely new alignment on the eastern edge of the state, running from Calais to Madawaska at a border crossing with Edmundston, New Brunswick.
The initial 1925 plan for the U.S. Route system took US 1 along the better-quality inland route (then Route 15)[5] between Bangor and Houlton, and placed US 2 on the coastal route.[6] This changed in the final 1926 plan, when the inland shortcut—now generally followed by I-95—became part of US 2.[7]
The portion between Portland and Brunswick was rebuilt, mainly as a four-lane divided highway, in the 1950s, and later absorbed into I-95 (now I-295). A freeway from Brunswick east to Bath was built in the 1960s.
