I'm flying to Vancouver for a conference. Are US dollars widely accepted or do I need to change money at the airport? Thanks for your help.

I suggest you check with your bank and see what kind of fees it slaps you with for off net transactions.

For example, I use Bank of America for checking and withdrawals of cash.
If I make an off net withdrawal, I pay $5.00 service fee for each transaction. If I go to Scotia Bank, I don't pay the fee.

If you know that situation is favorable, I suggest strongly that you withdraw local currency from an ATM.

To give a parallel situation, do businesses where you live commonly accept Canadian dollars for goods and services?

Where I live they do not and would not.

Besides the US dollar is no longer the world's dominant currency; the euro is.

BB has given you some good advice. let me just add one thing.

No, you can't use American dollars in Canada, but your best bet is NOT to change them at the airport at one of those unaffiliated ATM's EVEN if you do arrive without Canadian money in your pocket.

As it is a conference, I am assuming you will be on an expense account so take a taxi or limo from the airport to your hotel and charge it to your credit card...this is pretty standard procedure-they take VISA and MC and (mostly) AMEX, too.

Then, when you get to the hotel, get the concierge to direct you to the closest ATM that IS bank-affiliated--TD/Canada Trust, BMO, Scotiabank, we have way fewer banks than in the US and they all take Interac/CASH debit cards...you wll still have to pay whatever fee your bank finds lucrative, but what can you do?

Actually, Canadian dollars are accepted at many of my local establishments but certainly not by cabs or small shops. Thanks for the advice. I'll be sure and check out fees before leaving.

That IS also good advice about the independent, non bank-owned ATMs.
You probably will have a few dollars taken off your account that do not show up in your hand.

To add one more item, I travel about once a year out of the country and out of state a little more often.

I got weary of paying $5.00 for something that could be avoided.
Granted it is not a huge amount, but after a year of such fees I am probably poorer by $75.00 or so.

If I saw %75 lying on the sidewalk I would scarf it up as quickly as possible.

To combat the Bank of America add-on, I opened a money market account at Fidelity Investments.
To date, I have paid no fees. So far so good.

I also use a Capital One credit card to avoid paying 3% to Bank of America for a surcharge on all credit card transactions that are non dollar denominated.

I recently found that my local bank in Washington State houses Canadian currency at certain branches. They told me if I'm not picky about what bills I get, I can just stop in and they will give me what I need at the going exchange rate. If I wanted to order certain bills or a large amount of cash, then there is a separate fee and I'd need to order ahead and wait for them to get the cash in.

Some places we have made reservations want to be paid in cash and it would probably be more than we could get via ATM so we figured having some Canadian currency before arriving would make sense for us.