In 1931 he and his partner Glen Minaker gained fame for guiding wealthy American hunting parties and exploratory parties of all kinds, north and west of Fort St. John, where he had taken up ranching. Word had got round that here was a guide of remarkable ability. Thus, Mrs. Mary Henry engaged him as her guide on her first and also her next two trips into the “white areas” on the map. It seems odd to think that less than forty years ago so much of the area north of the Peace River Block was yet unsurveyed.
On the first Henry expedition in 1931, guiding and surveying as he went, McCusker explored a route from the Halfway River to the Liard Hot Springs. On Mrs. Henry’s fourth trip in 1935 the party pushed on to McDame Creek of ‘Klondyke Trail of ’98’ fame, and still further, to the Pacific Ocean.
Already in 1935 there was talk in the United States of a land road to link “Stateside” with the American territory of Alaska. Things were happening in Europe that foretold World War II. McCusker and Minard in the slack season in the winter of 1935-36 plotted a possible course for such a highway through Lower Post, although two other routes (at least) were favored at the time. At the same time an air route was being planned, also different from one eventually taken, at the insistence of flyer Grant McConachie, on the safer side of the Rockies. When McConachie set up his first airmail route and needed fuel dumps at various places including Fort Nelson, it was McCusker who laid out the winter road over which E.J. Spinney of Dawson Creek took the first tractor train in 1937. When war engulfed the United States seven years after McCusker prepared his map, the Northwest Staging route was built on McConachie’s flight route, laid out by McCusker. For this, he received the Certificate of Merit from the U.S. Public Roads Administration.
When the U.S. Army Engineers arrived in Dawson Creek in March 1942 to build the Alaska Highway (then called Alcan Highway) McCusker was already away by dog team, laying out the route of the “tote road” which eventually became the well-known Highway. For his knowledge of the otherwise “unknown country”, and for the maps already prepared, President Roosevelt decorated him with the “Order of Merit” for his contribution to continental defense.” Knox McCusker was a modest celebrity, with a host of friends across Canada and the United States.
Although nobody mentions her now, Mrs. Mary Henry could be called the Founder of the Alaska Highway, for it was she who sparked the trip into the Hot Springs, and the one on to the coast, which gave McCusker the chance to compile so much important information. McCusker was released from the Dominion Lands survey at the time he mapped the so important Alcan route. He died in Fort St. John in 1955 at the comparatively early age of sixty-five.