Panama Canal
Colombia, France, and later the United States controlled the territory surrounding the canal during construction. The US continued to control the canal and surrounding Panama Canal Zone until the 1977 Torrijos–Carter Treaties provided for handover to Panama. After a period of joint American–Panamanian control, in 1999, the canal was taken over by the Panamanian government. It is now managed and operated by the government-owned Panama Canal Authority.
Panama Canal Zone
Through the remainder of the 19th century, the United States landed troops several times to preserve the railway connection. At the same time, it pursued a canal treaty with Colombia (as New Granada was renamed). One treaty, signed in 1868, was rejected by the Colombian Senate, which hoped for better terms from the incoming Grant administration. Under this treaty, the canal would have been in the middle of a 20-mile zone, under American management but Colombian sovereignty, and the canal would revert to Colombia in 99 years. The Grant administration did little to pursue a treaty and, in 1878, the concession to build the canal fell to a French firm. The French efforts eventually failed, but with Panama apparently unavailable, the United States considered possible canal sites in Mexico and Nicaragua.