Nearly 20 million Americans are employed by state and local governments across the country. With so many workers, it’s almost impossible to keep everyone honest. Waste, fraud and abuse can cost taxpayers millions.

But in Oregon, strong oversight and audit rules ensure that state officials keep their hands out of the cookie jar. Data from the Justice Department, compiled by political scientists at Indiana University at Bloomington and the City University of Hong Kong, show that, over a period of 32 years, there were fewer corruption convictions in Oregon than in any other state, when controlling for the number of state workers.

Oregon registered 1.28 corruption convictions per 100,000 public employees between 1976 and 2008. Washington, Minnesota, Nebraska and Iowa also had fewer than two convictions per 100,000 employees.

Those states score well because of robust transparency laws, according to ethics watchdogs. Oregon’s rules for campaign finance disclosures are among the toughest in the country, and lobbyists and special interest groups cannot give gifts worth more than $50 to state employees. Oregon also requires most public-improvement contracts to be awarded based on competitive bidding, avoiding no-bid contracts, which can be a major source of corruption.

“An awful lot of corruption comes from government contracts,” said Melanie Sloan, a former federal prosecutor who runs Citizens for Responsibility and Ethics in Washington. “You can’t have no-bid contracts. You have to have transparent contracting procedures.”

At the bottom of the list, Mississippi, Louisiana and Tennessee all registered more than four times more convictions than the least-corrupt states.

More than 7,000 state and local officials were charged with corruption between 2003 and 2012, the Justice Department said in a 2013 report to Congress. The U.S. attorney for the District of Columbia reported 336 federal convictions over that time period; New Jersey’s U.S. attorney reported 428 convictions; and the four U.S. attorneys who oversee Texas reported 775 convictions. By contrast, Oregon registered just 42 convictions during that period.

The bill for all that wrongdoing adds up: Corruption forces states to spend more on everything from construction and highways to corrections and police. But the authors of the study, John Mikesell and Cheol Liu, also found that states with higher rates of corruption tend to spend less on education, public welfare, health and hospitals. So more corruption costs taxpayers – in terms of money and the social services the government provides.

Nine of the 10 most corrupt states, the authors found, could have saved $1,308 per resident if their corruption rates fell to the national average. Those states should look to Oregon, home of the most honest government workers in the country.

Malfeasance by the numbers:

7,000-plus: State and local officials charged with corruption from 2003 to 2012

775 convictions in Texas

428 convictions in New Jersey

336 convictions in Washington, D.C.

82 convictions in Washington state

42 convictions in Oregon

Note: Convictions from 2003 to 2012.

Source: Justice Department, www.justice.gov/criminal/pin/docs/2012-Annual-Report.pdf

Wilson is the author of Read In, The Washington Post’s new morning tipsheet on politics.