Post-colonial Panama 

In the first eighty years following independence from Spain, Panama was a department of Colombia. The people of the isthmus made several attempts to secede and came close to success in 1831, and again during the Thousand Days War of 1899–1902. When the Senate of Colombia rejected the Hay-Herran Treaty, the United States decided to support the Panamanian independence movement. In November 1903, Panama proclaimed its independence and concluded the Hay/Bunau-Varilla Treaty with the United States. The treaty granted rights to the United States "as if it were sovereign" in a zone roughly 10 miles wide and 50 miles long. In that zone, the U.S. would build a canal, then administer, fortify, and defend it "in perpetuity." In 1914, the United States completed the existing 83-kilometer (52-mile) canal. The early 1960s saw the beginning of sustained pressure in Panama for the renegotiation of this treaty.
From 1903 until 1968, Panama was a constitutional democracy dominated by a commercially oriented oligarchy. During the 1950s, the Panamanian military began to challenge the oligarchy's political hegemony.