Bulgaria–Romania border

The Danube

For 294 miles the border follows the main navigation channel of the Danube, which usually runs closer to the Romanian bank. The Romanian side is low, with long shallow lagoons; the Bulgarian side is mostly loess cliffs about 500 feet high. The river has about 90 islands and in the 1960s froze over in roughly three winters out of four.^[1]

The river was a barrier as much as a boundary. In 1965 the only bridge was the double-deck road and rail bridge between Giurgiu and Ruse, with a few ferries elsewhere.^[1]

Dobruja back and forth

The Congress of Berlin in 1878 recognised Romania’s independence, created the Principality of Bulgaria and gave northern Dobruja to Romania, in exchange for Romania ceding Bessarabia to Russia. A European commission drew the Dobruja line from east of Silistra to the Black Sea south of Mangalia, and in 1880 adjusted it near Silistra to keep a road in Bulgaria.^[1]

Romania joined Bulgaria’s enemies in the Second Balkan War, and the Treaty of Bucharest of 10 August 1913 gave it southern Dobruja. Bulgaria took back all of southern and part of northern Dobruja in 1918, after Romania had to sue for peace in the First World War, but the Treaty of Neuilly of 27 November 1919 restored the 1913 line.^[1]

Between the wars Romania settled Romanians in southern Dobruja, and more than 45,000 Turks, mostly from the region, left for Turkey in the 1930s. Under Axis pressure, the Treaty of Craiova of 7 September 1940 returned southern Dobruja to Bulgaria, and Bulgarians and Romanians were exchanged across the new line. The 1947 peace treaty kept it.^[1]