As a result, there are no immigration checks between the two but there travellers arriving in Puerto Rico or the American mainland directly from the Virgin Islands are subject to border control for customs inspection. America also maintains interior checkpoints, similar to those maintained by Bhutan, along its borders with Mexico and Canada, subjecting people to border controls even after they have entered the country. The city of Hyder, Alaska has also been subject to internal border controls since the United States chose to stop regulating arrivals in Hyder from British Columbia.