The Panama Canal Zone (), also simply known as the Canal Zone, was an unincorporated territory of the United States, located in the Isthmus of Panama, that existed from 1903 to 1979. It was located within the territory of Panama, consisting of the Panama Canal and an area generally extending on each side of the centerline, but excluding Panama City and Colón. Its capital was Balboa. The Panama Canal Zone was created on November 18, 1903 from the territory of Panama; established with the signing of the Hay–Bunau-Varilla Treaty, which allowed for the construction of the Panama Canal within the territory by the United States. The zone existed until October 1, 1979, when it was incorporated back into Panama. In 1904, the Isthmian Canal Convention was proclaimed. In it, the Republic of Panama granted to the United States in perpetuity the use, occupation, and control of a zone of land and land underwater for the construction, maintenance, operation, sanitation, and protection of the canal. From 1903 to 1979, the territory was controlled by the United States, which had purchased the land from its private and public owners, built the canal and financed its construction. The Canal Zone was abolished in 1979, as a term of the Torrijos–Carter Treaties two years earlier; the canal itself was later under joint U.S.–Panamanian control until it was fully turned over to Panama in 1999. History Proposals for a canal Proposals for a canal across the Isthmus of Panama date back to 1529, soon after the Spanish conquest. Álvaro de Saavedra Cerón, a lieutenant of conquistador Vasco Núñez de Balboa, suggested four possible routes, one of which closely tracks the present-day canal. Saavedra believed that such a canal would make it easier for European vessels to reach Asia. Although King Charles I was enthusiastic and ordered preliminary works started, his officials in Panama soon realized that such an undertaking was beyond the capabilities of 16th-century technology. One official wrote to Charles, "I pledge to Your Majesty that there is not a prince in the world with the power to accomplish this". The Spanish instead built a road across the isthmus. The road came to be crucial to Spain's economy, as treasure obtained along the Pacific coast of South America was offloaded at Panama City and hauled through the jungle to the Atlantic port of Nombre de Dios, close to present-day Colón. Although additional canal building