U.S. citizens traveling to Turkey need to have a valid passport
and Turkish visa to enter Turkey. Visa can be obtained in advance
or upon entering the country. Many people get their visas at the
airport once they arrive in Turkey.
Upon arrival, travelers are directed to visa stands, where U.S.
citizens get their visa stamp on their passports in return for a
visa fee of $20, which is valid for 2009. Please check Turkish
Ministry of Foreign Affairs web site for changes in visa fee for
2010 and onwards at
http://www.mfa.gov.tr/sub.en.mfa?cc4e437c-6769-4d79-9017-10b63c651224