The answer depends upon which country you planning to visit. A passport is required by many countries upon entry to their country. Also, a document indicating proof of citizenship is always required to re-enter the United States. A passport is an official government document that certifies one's identity and citizenship. A visa is an official government document that temporarily authorizes you to be in the country you are visiting.
Many countries require a visa to gain entry.
The State Department can take over 6 weeks to process your passport. The United States Passport Service, which is part of the State Department processes over seven million passports each year. There are fifteen national offices around the country which process the seven million passport applications. Sheer volume alone does not allow the Passport Service to process the applications quickly, let alone within a week or so - which many of our customers demand. The website also indicates that expedited orders are returned within a week.