The Alberta government started a rat free program in the 1950s. This article is fairly comprehensive: https://www.alberta.ca/history-of-rat-control-in-alberta.

The Alberta government started a rat free program in the 1950s. This article is fairly comprehensive: https://www.alberta.ca/history-of-rat-control-in-alberta.aspx#jumplinks-1 https://www.alberta.ca/history-of-rat-control-in-alberta.asp...