Plan ahead. Find the passport office nearest you on the national State Department travel website. Research the section on expedited passports. If you are applying for a new passport, you will have to apply in person. If you are renewing your passport, you can apply by mail.
Be Prepared. Take all supporting documentation with you to the passport office. You will need two new passport photographs, your most recent passport, if you already have one, plus the fees associated for a new passport or a renewal. If this is your first passport, you will need a certified birth certificate.
Go to the post office and purchase two Express Mail envelopes. After you apply, your passport application will be mailed in one envelope. Include the second envelope with your application. Your new passport will be mailed to you in the second envelope.
Be prepared to pay some extra money. Regular passport fees will apply, and there will be an extra fee for the expedited service.
Go directly to your regional passport agency, where the passports are actually issued. You can find a listing of these offices on the travel.state.gov website. If your trip is coming up, and you have to have the passport now, the only way you can sometimes get what you need is to show up there and stand in line. Call ahead of time, make and appointment, and make sure to bring exactly what the office tells you to provide.
If you can't wait two weeks, then try an expedited passport company, such as American Passport Express. These companies promise to have a passport to you in as little as 24 hours. Keep in mind that these are non-government, independent agencies, and you should conduct research on them before making use of their services.