Cross-border municipal issues involve matters affecting Canadian municipalities and their American counterparts on opposite sides of the Canada-US border. Border cities like Windsor-Detroit, Niagara Falls, and Sault Ste. Marie share economic regions, environmental resources, and community connections that span the international boundary. Issues may include border crossing infrastructure, environmental quality (shared air and water), economic development coordination, and emergency response collaboration. While international relations are federal jurisdiction, the federal government may mediate or facilitate cooperation between border communities. Some border municipalities maintain formal relationships with their counterparts to address shared concerns.