Correct answer: Panama had to gain its independence from Colombia, with US support.
Details:
As reported by the Office of the Historian of the United States: "President Theodore Roosevelt oversaw the realization of a long-term United States goal—a trans-isthmian canal" across the Isthmus of Panama. With Teddy Roosevelt in the White House, in 1902 the US Senate approved the building of a canal through Panama. Roosevelt's Secretary of State then went to work to arrange a treaty with Colombia (then in control of the Panama region). When Colombia ended up rejecting the US's offer because they thought the financial offer too low, President Roosevelt sent US naval warships to support the cause of Panama's independence from Colombia. After Panama achieved independence (with US support) in 1903, the new country, the Republic of Panama, agreed to treaty terms with the US for the building of the canal. The Panama Canal was completed in 1914.
During the High Middle Ages, which began after 1000, the population of Europe increased greatly as technological and agricultural innovations allowed trade to flourish and the Medieval Warm Period climate change allowed crop yields to increase.
