America/Canada is a slash pairing between the two North American nations: America (Alfred F. Jones) and Canada (Matthew Williams).
This pairing is referred to as AmeCan, primarily, (America and Canada), although alternatively called UsCan, CanAme, and Americest.
The pairing is based on geographic location of the two nations, historical occurrings between the countries, and the brotherly bond between the two. In addition, in the anime and manga, Canada and America are often seen together.
This pairing is often associated with France/Britain.