[2] Mansbridge was the lowest crossing point of the river until the early 18th century, when the Itchen Ferry began operating between Woolston and St Mary's, downriver of Northam.

[2] The Northam Bridge was the idea of David Lance, who acquired land in Bitterne and built Chessel House there in 1796.

[2] The Northam Bridge Company was formed in 1796, funded mainly by Portsmouth businessmen.

[2] The new route between Portsmouth and Southampton would be four miles (6 km) shorter than travelling via Mansbridge, and as a result the proposal to improve transport between the two important port cities was keenly supported by the Admiralty, especially since this was the time of the Napoleonic Wars.

[8] It was this change of ownership that allowed the first bus route across the River Itchen to be established in Southampton; Southampton Corporation decided against extending the existing tram lines across the bridge, opting instead to establish a double-decker bus service.

[11] The main deck structure has transverse diaphragms and narrowly spaced beams, which were pre-cast on site using deflected cables.

[11] These, together with in situ diaphragms between the ends of the beams, allowed the deck structure to be made continuous for live and superimposed loads.

[13] The bridge is reportedly haunted by the ghost of a soaking wet young girl.