Early proponents of a borderless international park include Canadian George "Kootenay" Brown, a long-time settler and first forest ranger-in-charge of Waterton, and American Albert Henry "Death-on-the-Trail" Reynolds, an early ranger of the northern portion of Glacier.

[1] The Cardston, Alberta, and Montana Rotary Clubs played a significant role in the park's establishment, holding a joint meeting at the Prince of Wales Hotel on July 4–5, 1931, which led to a resolution drafted by Samuel H. Middleton, calling on both groups to petition the proper authorities for the establishment of the Peace Park.

[2] An agreement was subsequently negotiated by Canadian Brigadier-General John Smith Stewart, Member of Parliament for Lethbridge, and American Congressman from Montana Scott Leavitt.

The Canadian federal government decided to wait until after the United States government had passed a bill in order to act, and the Canadian bill was further delayed by protests of proponents of the International Peace Garden between Manitoba and North Dakota.

Finally, John Stewart's Act respecting the Waterton-Glacier International Peace Park was passed by Parliament, and given royal assent on May 26, 1932.