With all the rhetoric over President Donald Trump’s interest in potentially taking over Greenland, WTOP asked a local history professor about the nation’s practices and patterns in this regard.

Jasmine Noelle Yarish, a history professor at the University of the District of Columbia, said that though it has not happened in a while, the United States is known for acquiring territories either by purchase, cession, annexation or conquest.

She said the first such acquisition for the brand-new nation in 1791 was when Vermont, a previously independent nation, became the 14th U.S. state after the original 13 colonies.

“What’s really interesting about that one is that the agreement was that Vermont would not enter into the United States unless it was determined to be a completely free state, so there was never a history of enslavement,” Yarish said.

She said the largest acquisition of property was in 1803, when the United States acquired the territory of Louisiana from France for $15 million through the Louisiana Purchase. It effectually doubled the size of the United States.

Other purchases that resulted in the U.S. acquiring large amounts of land include the Alaska Purchase from Russia in 1867 and the purchase of the U.S. Virgin Islands from Denmark in 1917.

“A lot of these particular purchases … like Guam, Puerto Rico, those acquisitions were driven by a much more globalizing world,” Yarish said.

The U.S. has also acquired territories through annexation. Those include the Republic of Texas in 1845 and Hawaii in 1898.

And some were taken through occupation, such as the Philippines and Guam after the Spanish-American War. The Philippines became an independent nation in 1946.

Yarish compared the current conversation regarding Greenland to a period in 1848, when America expanded west for precious metals and minerals.

“The acquisition of what becomes California, the Gold Rush. What we’re seeing now with the question of Greenland feels closer to that,” she said.