Well if you are only worried about illegals but Terrorists well see The U.S. Customs and Border Protection agency office says you are wrong and I am right:
Canadian Border Bigger Terror Threat Than Mexican Border, Says Border Patrol Chief
And as far as Alaska goes once we secure the lower 48 we can work on a plan for Alaska.
Illegal aliens are part of the problem not the only problem securing our borders means keeping out the nutters with chemical and biological weapons and shoulder fired missiles to take down planes etc. Right now they can sneak onto Canada's borders and drive across the Northern Border and we would never know.
We can build multiple Border Guard/military bases on both borders and give some much needed jobs to younger adults and they would be doing something useful. It is a win/win situation. Doing nothing on the Northern Border is defeatism/liberal dogma.
Regardless, a wall is not necessary to stop terrorists from coming into the US. Even the report you cited noted that CBP figures for fiscal year 2010 indicate that 447,731 illegal crossers were apprehended along the southwest border and 7,431 along the U.S.-Canada border.
No serious person suggests we build a wall on our Northern border. Can you cite anyone who recommends that?