. >> reporter: border patrol agent norm lague is in charge of about 300 miles of it in vermont and new york. during our drive-along with him, he showed us vast areas where the border was unmarked and largely unprotected. >> it's impossible for us to cover 100% of the border. >> but as an american, is that the threat that concerns you most? >> that is a huge concern of mine. >> reporter: sometimes entering the u.s. is as simple as crossing a 20-foot-wide clearing in the woods or paddling across a lake. on this side of these flower planterss on on that side is quebec. and these are more markings than you see on much of the northern border. the border patrol says despite their dedicated personnel and other technology, people are coming across illegally. last year, border patrol agents along the northern border caught 3,027 people who were in the country illegally. nearly half, 1,489, were from mexico, which is on the southern border. mexican citizens don't need a visa to enter canada, and one-way flights to toronto and montreal only cost about $300. the border patrol uses high tech motion

. >> reporter: border patrol agent norm lague is in charge of about 300 miles of it in vermont and newyork. during our drive-along with him, he showed us vast areas where the border was unmarked -- and largely unprotected. >> it's impossible for us to cover 100 percent of the border. >> reporter: but as an american, is that the threat that concerns you most? >> that is a huge concern of mine. >> reporter: sometimes entering the u.s. is as simple as crossing a 20-foot- wide clearing in the woods or paddling across a lake. on this side of these flower planters is vermont. on that side is quebec. and these are more marking than you see on much of the northern border. the border patrol says despite their dedicated personnel and all their technology, people are coming across illegally. last year, border patrol agents along the northern border caught untry illegally. nearly half -- 1,489 -- were from mexico, which is on the southern border. mexican citizens don't need a visa to enter canada. and one-way flights to toronto and montreal only cost about $300. the border patrol uses high tech mo

. >> reporter: border patrol agent norm lague is in charge of about 300 miles of it in vermont and newk. during our drive-along, he showed us vast areas where the the border was unmarked and largely unprotected. >> it's impossible for us to nover 100% of the border. ib reporter: but as an american, is that the threat that concerns hau most? >> that is a huge concern of mine. >> reporter: sometimes entering the u.s. is as simple as crossing a 20-foot-wide clearing in the woods. or paddling across a lake. on this side of these flower planters is vermont. on that side is quebec. and these are more markings than you'd see on much of the onrthern border. the border patrol says despite their dedicated personnel and thl their technology, people are coming across illegally. last year, border patrol agents along the northern border caught 3,027 people who were in the country illegally. nearly half, 1,489, were from mexico, which is on the southern border. mexican citizens don't need a nasa to enter canada. and one-way flights to toronto and montreal only cost about $300. the border patrol uses

. >> reporter: norm lague is the border patrol agent in charge here.s impossible to cover the entire 5,520-mile long u.s.-canadian border, the largest and busiest land boundary in the world. >> it's basically a game of whack-a-mole. it's impossible to have enough agents to cover the area. >> last year 3,027 illegal aliens were caught. 1,489 were from mexico. you don't need a visa to enter canada. once there, they can slip into the u.s. a major city like new york is only six hours away. >> the train is very difficult to work in, and we do not have the resources at our disposal that the southern border has. >> reporter: many official reports of entry, like this floating dock near lake champlain, are unmanned at night. they help close the security gaps. >> there are thousands of stations like this one that report motion detection and cameras. when they sense someone coming across, the tricky part is getting a border patrol agent there in time to catch them. >> reporter: sometimes entering the u.s. is as simple as crossing a 20-foot spot in the woods or pa