'Northland' Explores Life Along That 'Other' U.S. Border - NorthlandAt 5,525 miles, including Alaska, the northern border is the longest international boundary in the world. Without Alaska, the 3,987- mile line capping the Lower 48 is the third- longest. Politicians, federal agents, pundits, and most Americans focus on the line with Mexico, even though its northern cousin is more than twice its length and many times more porous. The only known terrorists to cross overland into the US came from the north. Fifty- six billion dollars in smuggled drugs and ten thousand illegal aliens cross the US- Canada border every year. Two thousand agents watch the line. Nine times that number patrol the southern boundary. According to a 2010 Congressional Research Service report, US Customs and Border Protection maintains “operational control” over just sixty- nine miles of the northern border.