Many countries require that a passport has a minimum of 6 months validity. Why don't you just get a new passport?

P_M,

The rule about land and sea crossings changed recently (last month?). You now need your passport or that new ID card for travel to Canada, and your passport for the Caribbean. It's needed to return to the U.S.

I used a passport expediter here in DC a few years ago and got the passport in 48 hours. It cost me about $100. You should be able to find an expediter who can do it in a few days.

FWIW - I'm not sure about the 3-4 weeks either. We had to renew our passports before our trip last year and got it in 10 days with expedited service using the Fed Ex option.