Canadians require a passport to cross the border.
You are allowed 180 days in the USA per calendar year.
If you are going to the states on a frequent basis
you need to fill out Form 8840. This shows a closer tie
to Canada than the USA. It is for tax purposes only.
If you do not fill out the form each year you "MAY"
be only entitled to 120 days. This form must be sent in
by the end of June each year. You need to fill in each
years number of days for the past three years.
Homeland Security is the department that limits the stay
to 180 days.
The Canadian Snowbird Association has been trying to get
us 240 days per year. This is known as The Canadian Retirement Visa.
There will be certain rules that pertain to getting one.
I have been snowbirding for many years and each year I make sure
I am up to date on all R and R's regarding crossing the border.