New data from CDC's National Center for Health Statistics show that the US teen birth rate dropped substantially between 2007 and 2015, but it has declined most slowly in rural areas. "From 2007 through 2015, teen birth rates declined 50% in large urban counties, 44% in medium and small urban counties, and 37% in rural counties," Brady E. Hamilton, Lauren M. Rossen, and Amy M. Branum report. They note that declines occurred in all states and in all major racial groups, but geographic disparities have persisted.
In a 2014 Guttmacher Policy Review article, Heather D. Boonstra investigated factors behind the drop in the US teen birth rate. She found that between 2003 and 2010, there was no evidence of reduced sexual activity by adolescents, but teens were using more contraception and more highly effective methods (such as IUDs and contraceptive implants) or dual methods (such as oral contraceptives plus condoms). She describes several factors that can affect contraceptive use, from economic conditions to school sex ed classses, and I think this paragraph is particularly worth highlighting:
[A]dolescents who are sexually active need easy access to contraceptive services. Expansions in public and private health insurance under the Affordable Care Act mean that more teens are gaining coverage for contraceptive services. Nevertheless, publicly supported family planning centers continue to play an especially important role for teens, in part because of their promise of confidentiality for all their clients. In 2010, these health centers served nearly 1.5 million teens and helped teens prevent 360,000 unintended pregnancies; 190,000 of these would have resulted in unplanned births and 110,000 in abortions.
Access to services from Title X-funded providers could be a factor in the urban-rural disparities in teen birth rates. In a survey of Title X-supported clinics in Great Plains and Midwestern states, Summer L. Martins and colleagues found that rural clinics were less likely to offer walk-in appointments, evening or weekend appointments, and on-site provision of hormonal contraceptive methods -- all of which can make it more likely for a young woman who decides she wants contraception to end up getting it. It's understandable that clinics in less-dense areas might not find it financially feasible to offer extended hours or keep all methods of contraception in stock. Increasing funding for rural Title X providers could make contraception more accessible to rural teens, but that seems unlikely in the current climate.