Missouri is a battleground state that is closely contested in almost every national election cycle.
In 2008, only 4,000 votes separated Democratic candidate Barack Obama from Republican rival John McCain.
But Tuesday's 71 to 29 percent blowout vote on Proposition C left no doubt where voters stand as they handed President Obama's health care law a stunning rejection.
The proposition attempts to protect Missourians from the new federal mandate to buy insurance.
It also tries overturning the new federal prohibitions on insurance companies selling insurance directly to people.
The requirement to buy insurance and the prohibition on insurance companies selling directly to the consumer are two regulations that go to the very heart of the new health care law.
Americans were told that they had to accept these two insurance regulations because they were essential to lowering health care costs.
Yet, it is already clear that those claims are wrong. Even by their own estimates, Democrats now admit that the costs to the federal government are going to be hundreds of billions of dollars more than the $940 billion promised when the bill was passed.
The new health care law was supposed to make American companies more competitive and lower their costs, but it is now turning out that way. In fact, it appears that the opposite is true.
Company after company has had to report those higher costs to their shareholders. AT&T, Inc. faces a one-time charge of $1 billion, John Deere faces $150 million, 3M $90 million, Caterpillar $100 million, and Prudential a $100 million charge. These are just some of the well-known companies that have reported higher expected costs.
The costs are also going to be higher in other ways, too. Obama repeatedly promised: "If you like your plan and you like your doctor, you won't have to do a thing. You keep your plan."
But after the law was passed even The New York Times was forced to note: "That could come as a surprise to many who remember the repeated assurances from President Obama and other officials that consumers would retain a variety of health-care choices."
The broken promises over transparency, stripping out special interest deals, and forcing through a bill that was clearly opposed by the majority of Americans has, as the vote in Missouri shows, left many with angry.
The opposition is hardly limited to Missouri. Nationally, a Rasmussen poll finds that Americans favor repeal by a 58 to 37 percent margin.
Another new Rasmussen survey indicates that even liberal New Yorkers favor repeal by a 56 to 42 percent margin.
The blowout in Missouri on Tuesday was much bigger than the polls suggested and indicates that opposition to Obama's plan may be much deeper than people realize.
With similar votes coming up in Arizona and Oklahoma even more people will get a chance to show their opposition.
Missourians have given politicians a warning over how toxic Obama's health care law really is. If politicians don't run against the health care bill, they may will find that states like Missouri are no longer swing states.
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John R. Lott, Jr. is a columnist for FoxNews.com. He is an economist and was formerly chief economist at the United States Sentencing Commission. Lott is also a leading expert on guns. He is the author of several books, including "More Guns, Less Crime." His latest book is "Dumbing Down the Courts: How Politics Keeps the Smartest Judges Off the Bench" Bascom Hill Publishing Group (September 17, 2013). Follow him on Twitter@johnrlottjr.