Transport in the Union of Soviet Socialist Republics (USSR) was an important part of the nation's economy. The economic centralisation of the late 1920s and 1930s led to the development of infrastructure at a massive scale and rapid pace. Before the Soviet Union's collapse in 1991, there were a wide variety of modes of transport by land, water and air. However, because of government policies before, during and after the Era of Stagnation, investments in transport were low. By the late 1970s and early 1980s Soviet economists were calling for the construction of more roads to alleviate some of the strain from the railways and to improve the state budget. The Civil aviation industry, represented by Aeroflot, was the largest in the world, but inefficiencies plagued it until the USSR's collapse