The United States conquered and bought new lands over time, and grew from the original 13 colonies in the east to the current 50 states, of which 48 of them are joined together to make up the contiguous United Staes. These states, called the "lower 48", can all be reached by road without crossing a border into another country. They go from the Atlantic east to the Pacific in the west. There are two other states which are not joined to the lower 48 states.
The United States is the leader in many areas of technology and research.The land and people of the USA are also incredibly varied. Wherever you choose to study, you will encounter a regional culture rich in history and local traditions. For instance, the West Coast region has many beaches, outdoor activities, the people have a relaxed attitude and you will probably find many local international communities.Living and learning in the USA will exhilarate you. It will change the landscape of your life permanently.