CHAMPLAIN, New York — An unlined, single-lane road in rural upstate New York that dead-ends just feet from the northern border is at the center of an unusual international immigration phenomenon — people escaping the United States for Canada.

Approximately 50,000 people have used Roxham Road to walk into Canada over the past three years. Roxham Road is one of dozens in Clinton County alone that run directly into the border, but this one is where more than 90% of all illegal crossings into Canada along the 4,000-mile-long border from Washington state to Maine have taken place since 2016.