Fifty States in the Union
The United States is made up of 50 states. It is a number that has become a familiar part of American identity, reflected in the 50 stars on the national flag, one star for each state. Together these 50 states stretch across a vast area, from the Atlantic coast in the east to the Pacific in the west, and beyond.
The Last Two to Join
The count of 50 has not always been the case. The number of states grew steadily throughout American history as new territories joined the Union. The final two states were added in the same year, 1959: Alaska in the far northwest, and Hawaii out in the Pacific Ocean. Since 1959, no new state has been added, which is why the total has stood at 50 for well over half a century.
The 50 or 52 Confusion
A surprisingly common mistake is to think the United States has 52 states. The confusion usually comes from counting places that are part of the country but are not actually states. Washington, D.C., the nation's capital, is a federal district, not a state. Puerto Rico is a U.S. territory, not a state. People sometimes add these in and arrive at a higher number, but the official count of full states remains exactly 50.
Source
This article was written using information from Wikipedia.