Jackson made a significant contribution to the development of art in Canada, and was instrumental in bringing together the artists of Montreal and Toronto.

Some of his most important artistic development was at the Étaples art colony, which he first visited in 1908 with his New Zealand friend Eric Spencer Macky.

When Jackson returned to Canada, he settled in Sweetsburg, Quebec, where he began painting works such as the Impressionistic Edge of the Maple Wood.

Unable to make ends meet and discouraged by the Canadian art scene, he considered moving to the United States.

[8] After the purchase, Jackson struck up a correspondence with the two Toronto artists, often debating on topics related to Canadian art.

Dr. James MacCallum convinced Jackson to relocate to Toronto by offering to buy enough of his paintings for one year to guarantee him a living income.

Jackson was a welcome addition to the Toronto art scene, having traveled in Europe and bringing with him a respected – though as yet not particularly successful – talent.

An avid outdoorsman, Jackson became good friends with Tom Thomson, and the duo often fished and sketched together, beginning with a trip to Algonquin Park in fall 1914.

[9]: 25  Inspired by Thomson, Jackson and the other painters who would one day be known as the Group of Seven undertook trips to Algonquin Park, Georgian Bay, Algoma and the North Shore.

[16] Jackson produced forty-five artworks for the organization, including the powerful A Copse, Evening (1918)--a grim depiction of the catastrophic effects of the First World War on the Belgian landscape.

In his opening speech, Jackson emphasized the right of the artist to paint what they feel "with utter disregard for what has hitherto been considered requisite to the acceptance of the work at the recognized art exhibitions in Canadian centres.

[20] It is through this kind of contact that he made lifelong friends of Beaver Hall artists Anne Savage, Sarah Robertson and Kathleen Morris.

He then began efforts at government lobbying, pleading in a letter to the minister of Lands and Forests William Finlayson to preserve from logging what became Killarney Provincial Park and Trout Lake.

Working with the National Gallery of Canada, he played a pivotal role in organizing the largest public art project in Canadian history: the Sampson-Matthews silkscreen print program in 1942.

[18] Jackson left the Studio Building in 1955 with Lawren Harris mourning, in a letter from Vancouver, "Your moving from the Studio Building marks the end of an era, the one era of creative art that has the greatest significance for Canada... You were the real force and inspiration that led all of us into a modern conception that suited this country, and the last to leave the home base of operations.

He returned to the Yukon in 1964, this time with fellow artists Ralph Burton and Maurice Haycock, traveling by plane over the landscape.

were painting on the banks of the Ottawa River at Deux Rivieres, a bullet ricocheted off a rock where Jackson was sitting.

"[32] In 1958, he published A Painter's Country,[34] an autobiography dedicated to the memory of Group of Seven member J. E. H. MacDonald, who "visualized a Canadian school of painting and devoted his life to the realization of it".

He recuperated at the home of friend and painter Ralph Wallace Burton, and later moved to the McMichael Conservation Estate in Kleinburg, Ontario.

Of Algoma, he wrote:Sketching here demanded a quick decision in composition, an ignoring or summarizing of much of the detail, a searching‒out of significant form, and a colour analysis that must never err on the side of timidity.