Leptogium rivulare is a rarely reported boreal-temperate cyanolichen widely distributed in glaciated portions of Asia, eastern North America, and eastern, central, and western Europe, between the 44°N and 60°N parallels. In the USA, its historical range extended as far south as Illinois and Vermont (possibly in glacial refugia) but records from the last 100 years are only from central Wisconsin. Here, we report the first records of L. rivulare in Minnesota from the Boundary Waters Canoe Area Wilderness, and from novel habitat in Ontario, periodically flooded bedrock shoreline of alkaline lakes. In Canada, it is federally listed as Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), and globally as Near Threatened by the International Union for Conservation of Nature (IUCN).