Sumas Lake covered roughly 4,000 hectares and reached across the international boundary into Washington. It was shallow and warm, thick with sturgeon, trout and salmon, ringed by wetland that pulled migrating birds down in enormous numbers. For the Semá:th, a Stó:lō people whose territory this is, the lake was not scenery — it was the food supply, and the rhythm of the year was built around it. After a catastrophic Fraser basin flood in 1894, the case for removing the lake altogether gathered force, and between 1920 and 1924 a scheme designed by BC Electric engineer Fred Sinclair carried it out. The Chilliwack River was diverted west into a newly cut Vedder Canal; the lake itself was drained through the Sumas Drainage Canal into the Fraser near the northeastern flank of Sumas Mountain. The works ran massively over budget. They also stripped the Sumas First Nation of the resource their community had rested on, and a specific land claim for the former lakebed has been pursued for decades since.

The Royal Engineers surveyed this country in 1858, pulled in by gold on the Fraser, and the road they laid out — Yale Road, now Old Yale Road — became the first route to link the valley end to end. Butter, milk and tobacco were coming off the land by the late 1860s. In 1889 a former Royal Engineer named John Cunningham Maclure applied for a Crown grant on the 160 acres that would become the town. Where the name came from has never been settled. The usual account credits Henry Braithwaite Abbott, western superintendent of the Canadian Pacific Railway and a family friend. Maclure's sons insisted the real source was Abbotsford House, Sir Walter Scott's home, and said their father put the stress on the second syllable. Maclure himself, late in life, said the naming had been a combination of two ideas.

The Gur Sikh Temple at 33089 South Fraser Way was built in 1908 and opened in 1911, and it is the oldest Sikh temple in North America — a distinction it holds partly by outlasting the competition. Vancouver's Second Avenue temple has been demolished. The Golden temple of 1905 burned. This one still stands, wooden and unshowy, a National Historic Site now well past its hundredth year. What it marks has since reshaped the city entirely. The 2021 census counted 43,190 Abbotsford residents born outside Canada, 28.6 percent of the population, and more than half of them — 23,830 people — came from India. Among Canadian census metropolitan areas, only the Greater Toronto Area and Greater Vancouver have a higher proportion of visible minorities than Abbotsford–Mission.

The city's coat of arms carries diagonal crosses, a visual pun on Abbotsford as a place where routes meet, with a strawberry blossom at the centre for the berry industry that has defined the valley floor for generations. The flag was blue until 1995, when the District of Abbotsford merged with the District of Matsqui to form the city as it now exists and the colour changed to green. That was the second amalgamation; the District of Sumas had already been folded in back in 1972. The result covers 375 square kilometres — more ground than any other city in the province — running from the slopes of Sumas Mountain down across the prairie to the international boundary itself. Sumas, Washington, sits directly across the line. Mount Baker fills the southeastern sky. For nine consecutive years Statistics Canada has named Abbotsford the most generous city in Canada by charitable donations.

In September 1984, Pope John Paul II celebrated an open-air Mass at Abbotsford International Airport before a crowd of more than 200,000 — larger than the city's entire population today. That airfield is still where Abbotsford gathers; the Abbotsford International Airshow has run there for decades and remains the event most outsiders associate with the place. Rail came first, though. A CPR line built through here in 1891 connected Mission with the Seattle, Lake Shore and Eastern Railway at Sumas, Washington, and until 1904 it was the only rail link between Vancouver and Seattle. The Village of Abbotsford was incorporated in 1892. The BC Electric Railway's Interurban tram reached the town in 1910 and ran until 1950, and its successor, BC Hydro, still holds the right to put passenger service back on the line.