No, domestic travels inside the US do not require you to show a valid passport. Any piece of photo ID is accepted.
Updating with more current information. Yes you now need a Canadian passport to travel to the US.
You don't need a passport to travel within the continental United States, even if you are not a citizen.
As a British Citizen you are able to travel freely within the boundaries of the EU, without requiring further visa's.
No. You only need to use a passport if you are traveling overseas. This doesn't mean that it's free to travel from state to state.
There are no requirements for Canadians traveling in the US just as US citizens don't need a passport to go to Canada although that is changing. Once you enter the US, you have met all the requirements according the US Border Control and the INS. You can travel freely just as any US citizen could. Of course for flying you would need some type of government ID just as a US citizen would to board a flight.
Canadians can only travel with the country of Canada without a valid passport. A valid passport or a valid permanent resident card are the two acceptable forms of documentation to re-enter Canada without issue.
A Canadian can drive across the U.S. border using one of several documents. It does not have to be a passport. Any of the following will suffice; passport, U.S. passport card, trusted traveler card, or enhanced driver's license.
I may be wrong, but all you need is an I-94 form and your Mexican passport as ID
Alaska is one of the 50 states of the United States of America. If you are a U.S. citizen you would not need a passport as you are traveling within the country... not to Canada.
You need a passport to travel almost anywhere that is not within your country.
No, you must be a citizen of the United States to be eligible for a passport from the US
If you are a Spanish National or a citizen of another European country then you do not need a visa to travel to Ireland. Anyone who holds a passport and is a citizen of the European Union is free to travel anywhere within the union.
If you are from the UK, then you do not need a passport to enter the Republic of Ireland, as they are within what's known as the "common British travel area" - allowing citizens of the British Isles to travel freely within the areas. However RyanAir may require a passport to prove that you are a UK citizen. Your best bet is to call RyanAir customer service and ask them.