the main opposition party in Italy, even if it would never return in government. For almost four decades, Italian elections were successively won by the DC, a centrist party. First Republic (1948–1994) 1950s and 1960s: post-war economic boom Under the Treaty of Peace with Italy, 1947, Istria, Kvarner, most of the Julian March as well as the Dalmatian city of Zara was annexed by Yugoslavia causing the Istrian-Dalmatian exodus, which led to the emigration of between 230,000 and 350,000 of local ethnic Italians (Istrian Italians and Dalmatian Italians), the others being ethnic Slovenians, ethnic Croatians, and ethnic Istro-Romanians, choosing to maintain Italian citizenship. Later, the Free Territory of Trieste was divided between the two states. Italy also lost all of its colonial possessions, formally ending the Italian Empire. In 1950, Italian Somaliland was made a United Nations Trust Territory under Italian administration until 1 July 1960. The Italian border that applies today has existed since 1975, when Trieste was formally re-annexed to Italy. In the 1950s Italy became a founding member of the NATO alliance (1949), a member of the United Nations (1955) and an ally of the United States, which helped to revive the Italian economy through the Marshall Plan. In the same years, Italy also became a founding member of the ECSC (1952) and of the European Economic Community (1957), later developed into the European Union. At the end of the 1950s an impressive economic growth was termed "Italian economic miracle", a term that is still recognized in Italian politics. The impact of the economic miracle on Italian society was huge. Fast economic expansion induced massive inflows of migrants from rural Southern Italy to the industrial cities of the North. Emigration was especially directed to the factories of the so-called "industrial triangle", the region placed between the major manufacturing centres of Milan and Turin and the seaport of Genoa. Between 1955 and 1971, around 9 million people are estimated to have been involved in inter-regional migrations in Italy, uprooting entire communities and creating large metropolitan areas. At the same time, the doubling of Italian GDP between 1950 and 1962 Italians families used their newfound wealth to purchase consumer durables for the first time. In 1955, for instance, only 3% of households owned refrigerators and 1% washing machines, while by 1975 the respective figures were 94% and 76%. In addition, 66% of all homes had come to possess cars.