town center, and where NH 135 branches off to the west. After US 2 leaves to the west, US 3 continues north, roughly paralleling the course of the Connecticut River (which also forms the border with Vermont), through Northumberland and Groveton, where NH 110 ends. North of Groveton, US 3 continues to follow the river, through Stratford, North Stratford, and Columbia, until it reaches Colebrook, where it crosses NH 26 and meets the southern terminus of NH 145. Still following the Connecticut River north, US 3 passes through portions of Stewartstown and Clarksville. In Stewartstown, the road turns more directly east (still following the Connecticut River, which is no longer a boundary), before resuming a northeasterly direction through Pittsburg. Its last major intersection is at the northern terminus of NH 145. US 3 continues north for another , eventually reaching the Pittsburg–Chartierville Border Crossing, where the road crosses into Chartierville, Quebec, and becomes Quebec Route 257. In total, US 3 runs along the Connecticut River and its source lakes for approximately . Sections of US 3 in Colebrook are named after Scott E. Phillips and Leslie G. Lord, members of the New Hampshire State Police killed in the line of duty on August 19, 1997. History New England route Before the establishment of the U.S. Numbered Highway System, the section of US 3 and Route 3 from Orleans, Massachusetts, to Colebrook, New Hampshire, was part of the New England road marking system as New England Route 6. It was replaced in its entirety with the establishment of US 3 and Route 3 in 1926. Massachusetts US 3 in Massachusetts closely follows the route of the early 19th-century Middlesex Canal and Middlesex Turnpike. The modern Northwest Expressway was begun near Route 110 in Lowell before World War II. In the 1950s, it was extended south to Route 128 (later overlapped by I-95), and, by the 1960s, it was completed north from Chelmsford to New Hampshire. By 2005, the chronically congested four-lane road, largely with antiquated ramps around Lowell, was widened to six lanes (as it had been in Nashua, New Hampshire, a few years prior) with a breakdown lane on both the left and right sides of the road, and many interchanges were modernized in what was comically known as "The Big Wide", in reference to Massachusetts' other "Big" construction project (the Big Dig). The roadbed and bridges were built to