Poll numbers may show a tough road to the White House for Republican Donald Trump, but he appears to have a reliable base of support in the nation’s military communities.

Voters in counties with strong ties to the armed forces favor Trump over Democrat Hillary Clinton 49% to 34%, according to an analysis of NBC News/Wall Street Journal poll data from June, July and August. Over that same period, Clinton led Trump nationally 47% to 41% in that polling.

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The Republican nominee’s edge in those 89 counties largely located near military bases, categorized as military posts in the American Communities Project, may come as a surprise to those who have watched the campaign closely.

An NBC News|SurveyMonkey poll released Wednesday showed that Trump leads Clinton by 19 points – 55 percent to 36 percent – among current and retired military service members. But the ACP analysis shows a similar double-digit lead for Trump in communities where non-military support staff and family members live and work as well as troops and veterans themselves. The two candidates will participate in the first joint appearance of the general election campaign Wednesday night at NBC News' Commander-in-Chief forum sponsored by the Iraq and Afghanistan Veterans of America.

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Why is Trump leading in military communities? He has a few big points in his favor built into them.

First, America’s military post counties have been reliably Republican in previous elections. They’ve sided with the Republican candidate for president by double digits in every election since 2000.

Second, they hold large numbers of a key voter group for Trump, whites without a college degree. More than half their 25-or-older population is made up whites without a bachelor’s degree. That’s about six points higher than the national average and much higher than counties that lean heavily Democratic, such as the urban suburb counties that sit around major cities.

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In the 2016 presidential campaign in particular that’s a big difference. Trump has built his campaign on appealing to white voters without a bachelor’s degree, and polling has shown he’s done well with them, even at the expense of losing college-educated whites.

Military-heavy counties usually have fewer voters with college degrees because they hold lots of young people who passed on college because they weren’t interested in it or couldn’t afford it. Many in those military communities may be in the military to earn money to help with college after service. Regardless of the reason, however, the net impact is fewer white voters with college degrees and that is a net plus for Trump.

In the broader sense of the active duty military overall, only 7% of enlisted members have a bachelor’s degree and about 70% of active duty military is white, non-Hispanic. That’s a good set of demographics for Trump.

The military post communities are particularly important to the GOP for another reason: age. They are younger than the nation as a whole. The median age in the United States is 37.4 years. In the military posts the average median age is 34.9 years. For a party that has struggled to win over millennial voters, these counties represent a bright spot.

As the election nears this demographic lens may be the best way to look at the nation’s military voters.

Trump may have a rough relationship with large parts of the national security establishment or some military brass. But those are only small parts of the overall military vote. About 72% of the active duty military is between the ages of 18 of 30, according to the Department of Defense. That’s a lot of young voters.

So the nation’s military post counties are counterweights to the younger liberal voters in college towns around the country that lean heavily Democratic. They are incubators for the next generation of the GOP – younger, reliably Republican and looking very safe for Trump in November.