Can you travel freely through the Canada - USA border?
Relatively freely. With a Canadian or US passport, enhanced driver's licence, or a Nexus card, you can travel between the 2 countries quite easily. If you are a citizen of another country, you may require a visa first to travel between the two nations. EDIT: This is assuming you don't have a criminal conviction in one of the countries. If you do, your international travelling becomes much more difficult.
With a passport you can.
you need to report to border agents with passport. it is not like the EU.
Almost freely with a US or Canadian passport.
L. E. Gant
You can if you have a pass port, or a special drivers license that allows you to cross the boarder. I've done so a few times when I went with my husband on business trips.
I can, and have.
If you have a passport, it is pretty easy. If you don't, you can only come in to Canada (from the USA, if you are American), but, you cannot go the other way without one.
The 90 Year Old: Homeless, Unemployed, Virgin
No Canadians hate us worse than Iran