Bethany Mandel writes in the New York Post about the political implications of the declining American birth rate.

Turns out states across the Midwest and Southeast fare better than those in the Northeast and on the West Coast. South Dakota’s rate, the nation’s highest, was a full 57 percent higher than the District of Columbia’s, which was the lowest.

Women in more rural areas, it seems, are simply having more kids; urban women are falling behind. The correlations between “red” states and higher fertility rates and between “blue” states with lower rates is unmistakable for anyone familiar with the electoral map. The question is why.

A CNBC story about the Times’ data offers a clue. It breaks down the cost of day care by state. The most expensive place for care? You guessed it: Washington, DC — the least fertile place in the country. By contrast, the most fertile state, South Dakota, is among the three cheapest states to get care for your child.

It’s logical: Couples aren’t having as many kids because they don’t have enough time or money. Is it any wonder such limitations lead to fewer children born in more expensive areas of the country, areas where parents have to work longer hours to provide for the children they already have?

Also notable: The highest-fertility states — the Dakotas, Nebraska, Utah and Idaho — boast strong religious communities, which encourage larger families and advocate for the infrastructure necessary to support them. With healthy economies, lower costs of living and a robust support system, families in these states have the resources to grow and keep up our country’s demographics.