Michigan has just become a right-to-work state -- the 24th state to give workers the choice of whether or not they will pay union dues as a condition of working. Data from the last election indicate that this switch might be as important, or more so, than America's demographic shift toward minorities that has been much touted in the weeks after the election.

Elections are not as simple as demographics. Otherwise, how did Mitt Romney win Texas by 16 points and lose California by 23 when Texas has a larger percentage of both Hispanic and African-American citizens?

Two far more determinative characteristics are states' rates of unionization and welfare dependency.

Nationally, union membership stands at 11.8 percent of the workforce, while 17.5 percent of the workers in Michigan are unionized, down from 40 percent in the early 1960s. Union strength varies widely state by state, depending on state labor law. Union membership in the 27 states that allow forced union dues payments averages 14.5 percent of workers. Union membership in the 23 right-to-work states averages 6.6 percent.

Unions, especially government employee unions, pour hundreds of millions of dollars into politics at the federal, state and local levels, advocating for higher taxes, more government, and greater pay and benefits for their members. More importantly, they mobilize millions of people into a disciplined army of campaign workers, on behalf of mostly liberal candidates.

Romney won 19 of the right-to-work states. Obama only won four -- Iowa, Virginia, Florida and Nevada (which is actually heavily unionized within its casino industry). Of the 27 states with compulsory union dues, Obama won all but five: Alaska, Montana, Missouri, Kentucky and West Virginia.

Along with right-to-work laws, a state's welfare dependency also appears to be a stronger indicator of its voting behavior than mere demographics.

Of the 17 states and D.C. where per capita welfare spending is above the U.S. average, Obama won 16, Romney only two (Alaska and Wyoming). Of the 33 states with below-average welfare spending, Romney won 22 and Obama 11. Of the ten states with the least welfare spending, Obama won two, barely: Virginia, with its massive colony of federal workers in the north, and Florida, with its heavy concentration of seniors drawing Social Security and Medicare entitlements.

Interestingly, of the 17 states with above-average per capita welfare spending, only two (Nevada and Wyoming) have right-to-work laws. Although there may be many reasons for this, one is that unions act as cartels, restricting labor's access to the market and preventing those with marginal skills from becoming employed, thus inflating the ranks of those dependent on government.

And then there's the Senate picture. Republicans won eight of 33 contests in 2012, all of them in right-to-work states and only one (Nevada) in a state with above-average welfare spending.

Looking to 2014, of the 33 U.S. Senate races in the coming midterm, 13 are Republican-held, of which 12 are in right-to-work states that voted for Romney. Regarding welfare dependency, 12 of the 13 states with Republican seats up in 2014 are also below the national average. There isn't much room for Democratic improvement here. Of the 20 U.S. Senate seats up in 2014 held by Democrats, six are in right-to-work states: South Dakota, Iowa, Arkansas, Louisiana, North Carolina and Virginia. All six are also below average in per capita welfare payouts. Six seats would be enough to flip control of the Senate.

As conservatives who favor free markets over big government ponder the lessons learned from the election, they'd do well to give union power and welfare policies as much attention as immigration and gender gaps.

Chuck DeVore is vice president of communications at the Texas Public Policy Foundation and served in the California legislature for six years.