For the first time in nearly 75 years, voters here in the nation's second-largest city have approved fundamental changes in how their much-maligned government works.

Only about 20 percent of eligible Los Angeles voters turned out at the polls Tuesday to consider the question of "charter reform," political shorthand for one of the most contentious and complex issues ever placed on the local ballot. The city, in essence, has rewritten its constitution.

The process may have been too dull to turn many heads in the land of movie stars and endless summers, but the result could profoundly affect local politics. It is the latest example of U.S. cities trying to confront chronic problems and changing economies with new forms of governance.

The measure passed with 60 percent of the vote. It will give the mayor of Los Angeles the powers that chief executives in most other big-city governments take for granted, such as firing the police chief or other agency managers. It will also revamp the city bureaucracy, create neighborhood councils that have a voice in community issues and may enlarge Los Angeles' small city council.

"This is an exciting day for our city," Mayor Richard Riordan said today at City Hall. He thanked voters for "saying no to the status quo."

The changes had been a long time coming. The last time that Los Angeles took similar steps was in 1925, when it was hardly the multicultural metropolis it is now. Work on revising the city charter began in the early 1990s, when Los Angeles was rocked by riots, a recession and an earthquake -- and when discontent with the local government was widespread.

The well-financed campaign to change the charter has been one of Riordan's top priorities, and it won support from many of the most powerful and popular names in town, from media mogul Rupert Murdoch to basketball superstar Magic Johnson. Murdoch alone contributed $200,000.

Most city council members opposed the measure, saying they were worried that it would give the mayor too much authority. Labor unions, which usually play a key role in city elections, also had serious reservations. But political analysts said the measure easily won passage because of a growing sense across Los Angeles that the government is too antiquated to respond to urban problems or seize new economic opportunities.

For some of the same reasons, other large cities have given their mayors more power in recent years to overhaul failing public school systems.

"People want cities to be able to respond faster to these things now, and one way to do that is with more centralized authority in government," said Fernando Guerra, the director of the Center for the Study of Los Angeles at Loyola Marymount University. "Here most of the mayor's power has only been symbolic."

The benefits of the new city charter to Riordan, however, will be limited. The millionaire Republican businessman is wrapping up his second term in office in two years, and by law he cannot run again. Some of the changes in the city government's structure also will not take effect until next summer.