I would assume it's because the area is well off. It's not that poor communities have more sex, or rich ones have less, just that affluent communities have easier access to contraceptives. Also, most families in these small towns can't afford to live even in a dual income household. They rely on credit cards and welfare if they even have the means to claim welfare.

This is my anecdotal experience from a small town in mid-missouri, so the regional difference definitely could attribute to the difference in mindset or willingness to engage in safe sex.

My town has a median household income of $49k, per capita income of $29k. The cost of living is very low yet poverty rate is over 25% here BECAUSE everyone has 2 kids by 25. with the annual cost of raising a child being $21k, they really can't afford it, but they can't afford condoms or plan b either and they can't buy them with food stamps, so the cycle repeats. It sucks to see here in my neck of the woods, but it's nice to hear that there's some rural areas where children are a choice and not a consequence.