The boundary was settled in 1846, but decades passed before there was much on either side of it worth guarding. What made this particular spot matter was geometry. The land here is dead flat — the Halkomelem name behind Sumas is usually rendered as "land without trees" or "big flat opening" — and flat ground is where roads and railways naturally want to go. The same flatness has a cost. This is floodplain, drained by the Nooksack on one side and toward the Fraser on the other, and water has been recorded rising over it for as long as anyone has been writing things down. On 15 November 2021, an atmospheric river demonstrated the point with brutal thoroughness: roughly 85 percent of the homes in the town of Sumas were damaged, and hundreds of residents had to be rescued after a partial evacuation. The customs lanes sit on that same prairie.

Canadian enforcement began as one man working out of his own house. When the Fraser Canyon Gold Rush of the late 1850s pulled prospectors north, police reported goods crossing freely with nobody to collect duty on them. John Musselwhite became the first customs officer at Upper Sumas around 1890, operating from his private dwelling some 20 kilometres northeast of today's lanes. His successor, T. Fraser York, took the job in 1893 — part-time, because that was all the traffic justified. Canada opened a proper border station at Huntingdon in 1896. Then the bureaucracy began its long shuffle: York moved to the newly created Port of Abbotsford in 1912, which was itself housed in a spare room of the Canadian Pacific station; Huntingdon was demoted to an outpost that same year; Abbotsford closed in 1932; and Huntingdon was finally elevated to a port in its own right in 1948.

The railway changed the stakes. In 1891 the Bellingham Bay and British Columbia Railroad reached the line and met the CP, and almost immediately the crossing became one of the busiest smuggling routes on the western border. Opium moved through. So did diamonds. So did people — Chinese migrants shut out of the United States by the exclusion laws Congress had passed in 1882 and renewed thereafter, which barred Chinese labourers from entering legally and so guaranteed that they would enter some other way. They were, for the most part, labourers going around a door that American law had bolted against them by race. J. F. Flanagan took up duty as Sumas's first American customs officer that same year, 1891. Prohibition later added liquor to the traffic, and the station was upgraded in 1932 in response.

The American side has cycled through its architecture with some inventiveness. Customs rented space from 1907; when the road through Huntingdon was relocated in 1913 and left the office awkwardly stranded, a new station went up on the east side of Cherry Street the following year, with part of the ground floor leased out as an automotive repair shop. That building gave way to the 1932 upgrade, which in turn became inadequate by 1988 — and became the one they moved rather than demolished. The current American station was finished in February 1990. Canada's sequence runs in parallel: a concrete station in the 1930s, a brick-faced replacement in the mid-1950s, and the twin-wing facility standing today, opened in 1992. A NEXUS lane arrived in 2012 and was extended by 1.3 kilometres between 2021 and 2023. Officially, the Canadian office is Abbotsford–Huntingdon. It never closes, and neither does the American side.