The Scowlitz and Chehalis peoples once had large and famously-carved longhouse villages, long since destroyed by the encouragement of missionaries.

The opening of Fort Langley in 1827 downriver began changing the traditional patterns of life for the Scowlitz and Chehalis by the introduction of new goods and also an end to raids by the Euclataws Kwakwaka'wakw (Southern Kwakiutl) of Cape Mudge and other northern coastal tribes.

For a time, official maps of the area duly recorded the name as Carnarvon but almost all newspapers and diaries referred to it as Harrisonmouth.

Gold was found around Harrison Mills and as far downstream as the present site of Mission, but extraction was profitable only above Hope.

Meanwhile, Captain Menten built a small sternwheeler called the Minto to carry passengers between Chilliwack and Harrison Mills.

Before this, children had to cross the river by boat to go to school; this is how Maud Menten, one of Harrison Mills's most famous residents, was educated.

It was in these adjoining years of relative inactivity in the sawmill that Thomas and Eliza Kilby built and opened their famous store.

On October 10, 1910, Eliza Kilby closed the hotel, leaving it open as a boarding house for many years.

Somewhat surprisingly, the government stationed a ten-man bridge guard from the Duke of Connaught's Own Rifles at Harrison Mills for the duration of the war.

There was an expectation that the Rat Portage mill would be opening once more and transform the town into a busy commercial centre once again.

The fire was so intense that the railway had to be closed for a day, delaying Prime Minister Mackenzie King himself in Agassiz while repairs were made.

In 1924, the project began after numerous petitions by Acton Kilby (son of Thomas and Eliza who was by now running the store).

In 1921, Thomas Kilby began to recruit his neighbours to sign a petition to the Municipality of Kent urging construction.

By 1925, the farmers had organized in a committee that constructed a private dyke that consisted of a 3' wall from the Bateson Slough to the CPR tracks at the Harrison Mills railway station.