Delta grew through the addition of routes and the acquisition of other airlines. They replaced propeller planes with jets in the 1960s and entered international competition to Europe in the 1970s and across the Pacific in the 1980s. The logo of Delta Air Lines, originally unveiled in 1959, is reminiscent of the swept-wing design of the DC-8 airplanes. Often termed as the "widget" logo, the current version consists of two 3D triangles