Originally Posted by
FBinNY
Based on some incidents in the last few years, there's increased concern over the possibility of terrorists coming in through our very porous border with Canada. Moving check points around randomly inside of the borders is just another line of defense.
The border between say Florida and NY that some of the 9/11 highjackers crossed on the day is a lot more porous. None of the highjackers came through Canada, though they probably could have. But at least in that case they get the twice over. Coming from Maine to the WTC, not so much.