Get a fresh, new valid passport if you hope to travel anywhere outside of the U.S. Even travel to Mexico and Canada requires a passport, so if yours is out of date, you're out of luck. Although adult passports last for 10 years, you can renew the document by mail if the passport was issued when you were 16 or older, as long as it's issue date was no more than 15 years ago.
Fill out form DS-82, available on the passport section of the State Department's website, Travel.state.gov. This is the "Renew by Mail" form, which you're eligible for, if you can submit your old passport and it was not issued more than 15 years ago. If you've had a name change, you must be able to present legal documentation with your application.
Fill out the form online or by hand. Either way, you'll have to print out the form to sign and send in.
Take two passport photos to submit with your application at a photo processing shop.
Write a check to the U.S. Department of State for the applicable processing fees, listed on the State Department's Passport Processing Fees page.
Enclose a marriage certificate if your name has changed.
Insert the check, application form, passport photos and your old passport into an envelope. The State Department recommends a secure mailing service, like insured USPS services or independent couriers, due to the sensitivity of the documents enclosed.
Receive your updated, valid passport in the mail in about 4 to 6 weeks.
Fill out form DS-11 if your passport was issued more than 15 years ago or if you were a minor under the age of 16 when you first got it. If your name has changed and you don't have a legal document to prove it, you'll need to fill out this form, too. Don't sign the form until you're at the passport office.
Look up passport acceptance agencies in your area. This could be a post office, passport agency or other acceptance facility. The State Department website has a handy tool for finding agencies in your area.
Make an appointment at the acceptance facility, if they require it.
Gather your supporting materials. This includes a form of photo ID and proof of US citizenship. Both of these must be accompanied by photocopies that the acceptance facility can keep.
Take two acceptable passport photos at a photo processing facility to submit with your application. Some acceptance facilities, like the post office, can take the photos for you.
Write a check for the associated passport fees. You'll find the current fees listed on the Passport Fees page of the State Department's website.
Sign the DS-11 form when the representative at the acceptance facility asks you to do so.
Hand over the form and your supporting materials and expect to return for your passport in 4 to 6 weeks.