Registered nurses staged a one-day strike against Tenet Health hospitals in Florida, California and Arizona on Friday, demanding better working conditions and higher wages as the nation's labor movement has begun flexing muscles weakened by decades of declining membership amid business and government attacks. About 6,500 National Nurses United members walked out at 12 Tenet facilities after working toward a first contract for a year in Arizona and under expired contracts in California and Florida, the union said. They plan to resume working Saturday. Members passed out leaflets in Texas, where contracts at two Tenet hospitals in El Paso expire later this year. The Tenet walkout is one of several strikes and organizing efforts nationwide as unions work to rebuild from a steep membership decline that began 50 years ago. Many are focusing on white-collar, female-dominated and service-sector industries such as health care, teaching and the media, not just blue-collar, male-dominated industries like manufacturing, where the United Auto Workers is striking against General Motors. A recent Gallup poll showed Americans support unions by 2-to-1, up from a near split 10 years ago and nearly the highest level since the 1960s. About 30 nurses picketed outside Palmetto General Hospital in Hialeah, Florida, during intermittent rain Friday. They waved red flags with a white N and carried signs with such slogans as 'Happy RNs = Healthy Patients.' Yajaira Roman, a union leader and neurological intensive care nurse at Palmetto, said while Tenet nurses want higher wages — the company is offering raises of about $12 a week at Palmetto — they particularly want a lower patient-to-nurse ratio to avoid burnout and improve care. 'We are really proud of what we do and we're happy that we're serving the community, but we want to do it in a way where when patients leave the hospital they are extremely satisfied,' Roman said. In Tucson, Arizona, Fawn Slade said she and her colleagues want Tenet to work on nurse retention and lessen their workload so patients get optimal care. 'It's more important that our community recognizes that the nurses are here advocating for their safety,' Slade said. Tenet, which has 65 hospitals and 115,000 employees nationwide, said it has negotiated in 'good faith' and it is disappointed the union chose to strike. 'While we respect the nurses' right to strike, patients and their loved ones can be assured that our patients will continue to be cared for by qualified replacement registered nurses,' the Dallas-based company's statement said. According to the U.S. Labor Department, almost 3 million registered nurses are employed nationally, with an average annual salary of $75,510. Florida's average RN salary is $66,210, Arizona's is $77,000 and California's is $106,950, tops in the nation. Union membership has plummeted in the U.S. since the 1970s. About 10% of American workers are unionized today and only 7% in the private sector, down steeply from 40 years ago when a third of workers were represented, as jobs shifted from manufacturing to the service sector. When adjusted for inflation, the average American's wage has remained stagnant during those decades, according to the Pew Research Center. Government actions have also hurt unions. With support from business groups, Wisconsin and Michigan, both states with strong union histories, adopted 'right to work' laws this decade that prevent private-sector companies and unions from requiring employees to pay union dues or fees. Twenty-seven states , including Texas, Florida and Arizona, have such laws. The Supreme Court ruled 5-4 last year that government workers nationwide can't be forced to contribute to the unions that represent them in collective bargaining. Jeffrey Hirsch, a University of North Carolina law professor who specializes in labor issues, said such losses may spur unions to be more aggressive, but it also helps that unemployment is low. That makes workers more confident that a strike won't cost them their jobs. 'If the job market is better, they have more leverage because they aren't as easy to replace,' he said. Almost 50,000 General Motors workers went on strike this week as the UAW demands higher wages. It's the first U.S. auto industry work stoppage in a decade. In health care, 80,000 Kaiser Permanente workers plan a one-week strike next month to protest the hospital chain's wages and labor practices. Organizers say it might be the biggest U.S. walkout since 185,000 Teamsters struck United Parcel Service in 1997. Teachers walked out in several states over the last few years demanding higher salaries and more school funding, including in Oklahoma, Arizona, Kentucky and West Virginia. Unions have also organized at several newspapers, including the Los Angeles Times, and at websites such as BuzzFeed, Slate, HuffPost and Fusion. Mary Anne Trasciatti, chair of Hofstra University's labor studies program, believes unions will experience a growth period because of their improving public support, particularly among younger workers. She said people are realizing the manufacturing jobs of the 1950s and 1960s paid well because they were unionized. 'You've got people who are really struggling who are saying, 'Look our 'leaders' and our 'status quo' is not serving our needs' and they are pushing back,' she said. __ AP writer Astrid Galvan in Phoenix contributed to this report.