Interesting …
The pilot project with Canada, conducted from September to January, involved about a third of the traffic across the northern American border, tracking the departure of 413,222 foreigners from the United States. Starting this year, according to Congressional officials who have been briefed on the plan, the information collected at the Canadian border will be used to prevent certain foreigners who have stayed too long in the United States from returning again by revoking tourist visas or taking other steps.The effort relies on an ingenious solution: as foreigners leave the United States to enter Canada — and their passports are checked by the border authorities there — the information is sent back to the United States and recorded as the official “exit” record. By the end of next month, the project is scheduled to be expanded to almost all land border traffic between Canada and the United States.
via U.S. Tracked Foreigners Leaving for Canada – NYTimes.com.