After 10 years of construction, the Aswan High Dam across the Nile River in Egypt is completed on July 21, 1970. More than two miles long at its crest, the massive $1 billion dam ended the cycle of flood and drought in the Nile River region, and exploited a tremendous source of renewable energy, but had a controversial environmental impact. A dam was completed at Aswan, 500 miles south of Cairo, in 1902. The first Aswan dam provided valuable irrigation during droughts but could not hold back the annual flood of the mighty Nile River. In the 1950s, Egyptian leader Gamal Abdel Nasser envisioned building a new dam across the Nile, one large enough to end flooding and bring electric power to every corner of Egypt.