U.S. citizens will need a valid passport and a visa issued by the Russian government before entry. Visas are not available upon arrival and the application process is lengthy.
Russian visas are severely restricted and limit a traveler's stay in the country. The earliest date of arrival and expected date of departure are listed. Stays cannot exceed 90 days in a 180 day period.
Every traveler must have a sponsor. A sponsor can be a hotel, tour company, relative or employer.
An exit visa is required to depart from Russia. An overstay of even one day can result in heavy fines, arrest and/or deportation.
The U.S. Department of State warns that Russian regulations regarding foreign travel change regularly. In addition, the Russian government doesn't recognize U.S. authority to intervene in matters regarding visa violations and other travel issues.