A large region of land
To add or incorporate a new territory into a country
Something that is gained, or acquired
An American belief in the 1800s that it was a natural right of the US to expand west to the Pacific Ocean
An area of land set aside by the US government for the American Indians to live
A group of people sent to explore unknown places
A geographic line between two places, such as two countries or states
To give up territory, usually as a result of a treaty