The Panama Canal was built by the U.S. Army Corps of Engineers between 1904 and 1914; the existing 83-kilometer (50-mi.) lock canal is considered one of the world's great engineering triumphs. On January 5, 1909 the government of Rafael Reyes in Colombia signed and presented to its Congress a treaty that would officially recognize the loss of its former province, but the treaty was not ratified, due to popular and legislative opposition. Negotiations continued intermittently until a new treaty was signed on December 21, 1921 which formally accepted the independence of Panama.