If a passport expires in September of 2011, can one travel up until that time? Thanks

You can travel until March 2011.If you plan to travel after that date you would be wise to renew your passport as soon as you can.

If we are talking about going to Europe, it depends where you are going. Denmark and Switzerland have a 3-month rule and Belgium has a 6-month rule. I think that is why kismetchimera is saying March.

Passport renewals by mail seem to be pretty fast right now. We applied in late December and received them by mid January

um -- what country are you from? That could make a huge difference . . .

But in general, it is never a good idea to travel right up to a passports expiration date.

LOL, when I went to France with my UK passport in July last year, although it wasn't due to expire until the end of August, I got fed up with the number of people who told me that I needed to renew it, including the person who checked us in at the ferry-port!

when i did renew it, I got it back in a week.

Each country has its own rules as to how much longer validity your passport must have when you enter the country. You can usually find these rules by going through the website of that company's embassy in your home country. It's usually on a page named "consular affairs" or something like that about entry requirements.

If you are from the US, the state department has its own page where it compiles such information but understand that the rules are not the US rules and the state department may not always have the most up to date information for all countries.

http://www.travel.state.gov/travel/travel_1744.html

I would always check with the country you are visiting and then check again just before you go as the rules do change.

And -- if you are from the US -- why not just renew now? It only takes a week or two.

Technically, if you are a US citizen, you cannot renew your passport. You must apply for a new passport. Your old passport will be cancelled and returned to you. (Many folks like to have their old passports for the visa stamps.)

Thanks everyone, from Laurie Annes suggested site I found
ENTRY/EXIT REQUIREMENTS FOR U.S. CITIZENS: While some countries impose a minimum passport validity of three, six, or nine months for arriving passengers, there is no such requirement for the United Kingdom. U.S. citizens seeking entry as tourists or visitors are simply required to present a valid passport, as explained on the website of the UK Border Agency.
Does this mean We'll be OK?

OK - if you had said you were from the USA and if you had mentioned the UK -- answers would have been different. Hard to answer in a vacuum.

The UK in general only requires a valid passport. But once again, why not just renew now?

U.S. citizens seeking entry as tourists or visitors are simply required to present a valid passport, as explained on the website of the UK Border Agency.
Does this mean We'll be OK?>>

fine, so log as you can put up with eveyone "helpfully" telling you that it's about to expire.

You asked if you could travel "up until that time" and the answer is yes, you can; whether or not you can stay is another matter.

On arrival in Britain, a non-European foreigner is normally given leave to stay until 6 months after arrival, or the last day of his passport validity - whichever is earlier.

It's not unheard of for that day to be the day of arrival.