ADDIS ABABA, Ethiopia (AP) — Ethiopians are celebrating progress in the construction of a dam on the Nile River, which has caused regional controversy over its filling. In joyful demonstrations urged by posts on social media and apparently endorsed by the government, tens of thousands of residents flooded the streets of the capital Addis Ababa, waving Ethiopia’s flag and holding up posters. People honked car horns, whistled, played loud music, and danced in public spaces. Deputy Prime Minister Demeke Mekonnen called on the public to rally behind the dam and support the completion of its construction. Downriver countries Egypt and Sudan are concerned about how the dam’s operations will affect their water supply, but recent negotiations appear to have made progress.