UPDATE 1-UAW membership lowest since World War Two

(Adds comment from UAW)

DETROIT, March 28 (Reuters) - Membership in the United Auto Workers union has dropped below 500,000, hitting its lowest level since World War Two in a downturn that reflects the wrenching restructuring by U.S. automakers.

UAW membership dropped by 14 percent from the prior year to 464,910 in 2007, according to the union's annual report, which was released on Friday to the U.S. Department of Labor.

Membership in the union peaked at near 1.5 million in 1979 and has been declining since. Since 2001, the union has lost over a third of its membership.

The last time the UAW had fewer than half a million members was in 1941, according to labor historian Mike Smith of Wayne State University's Walter P. Reuther library.

By 1945, the union's ranks had increased to about 1 million members, Smith said.

The Detroit-based UAW negotiated historic contracts with General Motors Corp (GM.N: Quote, Profile, Research), Ford Motor Co (F.N: Quote, Profile, Research) and Chrysler LLC last year that allow the Detroit-based automakers to replace thousands of current workers with others at sharply lower wages.

But union officials have said that the number of hourly workers accepting buyouts and early retirement incentives on offer at all three companies has been much smaller than in 2006 when some 68,000 UAW workers opted to leave Ford and GM.

U.S. employment in the auto industry peaked at 1.1 million in 1999 but has since fallen by about 27 percent, according to the statistics compiled by the Ann Arbor, Michigan-based Center for Automotive Research.