The United Auto Workers (search) reached a tentative four-year agreement with the Chrysler arm of DaimlerChrysler (DCX) Monday but was still in talks on new labor pacts with General Motors Corp. (GM) and Ford Motor Co. (F)

The UAW, formed in 1935 in the midst of the Depression, is one of the largest and most powerful unions in the United States. By 1941, after bloody confrontations and a protracted battle with automotive pioneer Henry Ford, the union had won recognition by the major automakers.

The following is a brief chronology of some of the more important events in the history of the United Auto Workers union over the past four decades:

1964 — UAW wins first full hospital-surgical-medical benefits for retirees, along with life and disability insurance fully paid by the automakers.

UAW strikes for five weeks at General Motors plants, its first national strike against an automaker in 13 years, after GM resists concessions on health care and overtime rules.

1967 — UAW wins prescription drug plan for its members at the Big Three. Surviving spouses are included in the union's retiree health-care plan.

1970 — UAW wins so-called "30-and-out" benefits after a 10-week strike at GM. Benefit plan allows UAW hourly workers to retire with a pension.

Legendary UAW President Walter P. Reuther, a leader of the union's organizing drives at GM and Ford, dies in a plane crash.

1973 — Other Detroit automakers agree to "30-and-out" pension.

Health and safety programs established to reduce work-place hazards and injuries.

1979 — UAW-Chrysler workers agree to first in a series of concessions, including delayed raises and cost-of-living adjustments, to save the company from bankruptcy and mobilize to win loan concessions from the U.S. government.

1982 — Income security established for laid-off workers at GM and Ford.

UAW also wins profit-sharing for GM and Ford workers.

1984 — New job security pattern set in negotiations with GM including creation of so-called "jobs bank." This allows workers affected by layoffs to get training or non-traditional instead.

1987 — UAW wins moratorium on plant closings at GM and Ford, a ban matched a year later at Chrysler.

1990 — Job security enhanced for hourly workers at GM, Ford and Chrysler.

1996 — Job and income security funds increased.

1998 — UAW stages 54-day strike at GM parts plants in Flint, Michigan, to protest work outsourcing.

1999 — UAW wins 3 percent annual pay hikes for all four years of new labor contracts with Big Three automakers, for the first time in 20 years.

New moratorium on plant closings and spin-offs.

Sept. 15, 2003 — UAW reaches agreement with Chrysler on a new four-year pact. No details are immediately released. Negotiations continue with Ford and GM.