Answer:
The nation that was responsible for constructing the Panama Canal from 1906 to 1914, and overseeing the waterway until 1999 was the United States.
Step-by-step explanation:
The canal was built by the Panama Canal Company, which was owned by 1% by the government of the United States of America.
From 1903 to 1979 the territory was controlled by the United States, who built and financed the Canal. The decolonization of the territory began in 1979 and the Canal Zone became the Reverted Areas of the Panama Canal, an area of shared sovereignty between the United States and Panama. Gradually, these areas would be transferred to the Republic of Panama. The last American flag was lowered in Balboa on New Year's Eve 1999.