The two numbers that may matter most for Donald Trump

March 7, 2016, 9:40 PM UTC / Updated March 7, 2016, 9:47 PM UTC

By Dante Chinni

Forget the polls and the "momentum." There are two numbers that seem to be better measures when it comes to Donald Trump's candidacy: unemployment and African-American population.

In every state to vote on the Republican side so far, Trump wins in states where the African-American population is above 8 percent and the unemployment rate is above the national average (5 percent in December, the latest state numbers available). He's seven for seven in those states -- Alabama, Georgia, Kentucky, Louisiana, Nevada, South Carolina and Tennessee.

There are four states on the GOP menu Tuesday night, and going by those two numbers, Trump looks ready for a good night in the two biggest states on the list: Michigan and Mississippi.

To be clear, these aren't the only states where Trump wins. He's won in some states where the rule doesn't apply -- New Hampshire and Vermont, for instance. But other than those two states, all of Trump's victories have come in states where at least one of these two data points is true: They have either higher than average unemployment, an African-American population of above 8 percent or both those attributes.

And using this rule, Saturday's GOP contests make a certain amount of sense. The two states won by Sen. Ted Cruz, Kansas and Maine, are below the national unemployment rate with smaller African-American populations. Trump's wins came in Louisiana and Kentucky, which have both higher than average unemployment and more African-Americans.

What's behind the phenomenon? That gets a big tricky. Race and economic struggles are often closely tied.

As we noted recently, Trump did better in South Carolina in more racially and ethnically diverse counties than he did statewide, and that pattern has carried through to other states. He's not winning minority voters (there aren't many minorities who participate in Republican nominating votes) but rather white voters who live in communities with large minority populations.

Those white voters also tend to have lower incomes and fewer college degrees -- factors that also play a big role in unemployment.

Saturday's results showed closer races in Kentucky and particularly Louisiana than many expected. That may have something to do with the troubles Florida Sen. Marco Rubio has had in the polls. In both states Rubio got less than 17 percent of the vote, and that suggests a narrower field, which means Trump could face stiffer competition in the coming contests.

But the fact that the New York businessman still won in those states says that the unemployment/African-American rule still matters. Tuesday night will help tell us how much.

This article originally appeared on NBCNews.com.