California leads the nation in both the growth and overall number of charter schools, according to a study by the Washington-based National Alliance for Public Charter Schools.
California has approximately 1,000 charter schools, which make up just under 10 percent of all public schools in the state. Nationally, charters make up 5.8 percent of the total number of public K-12 schools.
"Even though charters in the state have been held back by funding inequality and lack of access to facilities, California has been able to develop the strongest ecosystem of charter schools and supporting organizations in the country," California Charter Schools Association president Jed Wallace told the Huffington Post. "When other states catch the charter bug, they come to California to learn how to do it."
Charter schools are legally independent and at least partially government-funded. Many in the education reform movement have held up charter schools as innovative ways to improve the school system by giving teachers and administrators increased flexibility.
In California, 109 new charter schools opened at the outset of the 2012-13 school year. More than one in every four charter schools launched last year in the U.S. was based in California.
There's also movement in the other direction. The report notes that 28 of California's charter schools closed in the last year. The reason behind those closures concerns the California Federation of Teachers, the state's largest teachers union.
"There have been a number of reports showing that the responsible government agencies tasked with regulating charter schools are having a difficult time keeping track of the quality of education provided," explained Gary Ravani, president of CFT's K-12 Council. "There's a significant cache of building new schools, but there's not a good system in place to monitor them."
Ravani pointed to an often-cited Stanford University study showing that 17 percent of charter schools outperform traditional public schools. He also noted that when charters close, often due to lack of funds, students are left in the unstable position of suddenly having to find a new school.
Wallace argued this process of creation and destruction is precisely what keeps California's network of charter schools healthy and functional. "The charter school recipe is freedom from bureaucracy in exchange for higher accountability," Wallace said. "If you look at the schools that closed last year, 60 percent were performing in the bottom tenth of schools in the state. … I think people appreciate that this level of accountability is acceptable."
Even so, these concerns are why the state teachers' union backed a bill introduced in 2011 by California State Assmeblyman Tom Ammiano (D-San Francisco) that would have put a hard cap on the total number of charter schools in the state and limited the percentage of charter schools in any given school district to 10 percent. The bill never made it into law.
A study released by the California Charter Schools Association last year found the state's charter schools have significant numbers of both high- and low-performing schools with relatively few rating in the middle. Wallace noted that such distributions are relatively common in states that had strong charter school regulation, like California.
A statewide analysis of California's charter schools conducted by the Rand Corp. found that "charter schools were cost-effective -- achieving academic results similar to those of traditional public schools even though they obtain less state and federal categorical funding."
Over the past five years, the U.S. has added 1,700 charter schools--an increase of nearly 50 percent from the 2007-2008 school year.
California was the second U.S. state to allow charter schools in 1992, after Minnesota. Other states that registered the most charter schools last year were Florida, Texas, New York and Michigan.