Complex sentence: No particular road in Canada has been officially or unofficially designated as the Pan-American Highway, although some unofficial claims have been made based on routes that are a natural extension of several key American highways that reach the Canadian border.
Split into simpler sentences: No particular road in Canada has been officially or unofficially designated as the Pan-American Highway. However, some unofficial claims have been made based on routes that are a natural extension of several key American highways that reach the Canadian border.