Portsmouth and Concord Railroad

By 1845, the state of New Hampshire had three north-south routes, all starting in Massachusetts and leading, respectively, to the capital of Concord, through southeastern New Hampshire to Maine by way of Dover, and along the coast via Portsmouth to Maine. However, a large gap existed between the Boston-Concord line and the Boston & Maine line through Dover. In response, two railway companies were founded in July 1845: the Portsmouth, New Market and Concord Railroad, and the Portsmouth, New Market and Exeter Railroad. Both were given the concession to construct and operate a rail line from Portsmouth to a point on the Concord Railroad between Manchester and Concord called Bow Junction. The companies merged on December 23, 1845, forming the Portsmouth and Concord Railroad. On July 10, 1846, the railroad was granted a license for a branch line from Hooksett to Suncook, then on June 23, 1848, a license for a branch line from Manchester to Candia.

The construction of the mainline from Portsmouth to Bow Junction began in Portsmouth in the summer of 1847. In August 1852, the approximately 50-mile (80 km) mainline was completed. The two branch lines were not initially built.