The contest is sponsored by CAA Manitoba but the letter mentions an organization that I didn't even know existed anymore: the Manitoba Good Roads Association. Based in Portage la Prairie, they appear to be websiteless right now, but Googling them finds that they are still active in promoting well maintained roads and related matters.
Likely not a winner: Hwy 6 Winnipeg to Souris ca.1922 (source)
The contest is not new. Here are the results from 1939 when the R.M.s of Strathcona and Odanah took top prizes. Pipestone and Hamiota won in 1941.
Winnipeg Evening Tribune, May 31, 1940 (full article)
The association was formed in 1909 and not just to give prizes. They advocated for improved commercial opportunities, road safety and even advocated for a share of gas tax revenue for road improvements as early as 1940 !
The first president of the association was Samuel Robert "S.R." Henderson. The Hendersons were a pioneering family from the North and East Kildonan area. He worked for many community organizations ranging from horticultural societies to John Black Church and served on the municipal council.
He presided over the Manitoba Good Roads Association for 18 years until shortly before his death in 1928. Fittingly, two roads were named for him: Henderson Highway and Essar Avenue (his first two initials spelled out).
The day after his death, Jan. 28, 1928, the Free Press wrote:
“He was always on the side of progress, looking ahead and anticipating good results and general benefits from some project that to others might have seemed without merit".
'Mr. Highways' Ace Emmett MB Historical Society
AC Emmett and Good Roads in Manitoba MB Historical Society
Movement for Good Roads Rapidly Growing in Popularity Portage la Prairie Weekly Review, June 8, 1910