Some of the cultural reasons why women might have their first child earlier in places like Taylor's (fictional Pittman County) rather than later in places like San Diego is because more women are expected to raise babies when they are younger because they are in a more rural place. The majority of women are expected to raise a baby their whole life, therefore, will most likely not go to college and drop out of high school to raise a baby.
For example, in the book The Bean Trees by Barbara Kingsolver on page 4, it states, “Believe me in those days the girls were dropping by the wayside like seeds off a poppy seed bun.” This demonstrates that girls in her high school were dropping out to raise their own babies. However, in San Diego women are taught to try and get a steady job to be able to support their child when they are done with school. Most women at least graduate high school to go to college, and were introduced to the idea since they were in middle school or late elementary school. This puts the thought into their head that they have to wait to have a baby after they finish school.
Some of the socio-economic reasons why women in more rural places usually have babies earlier than in places like San Diego are because women have more options on what they can do later in their lives. For example, they have more potential options to do rather than become a parent and raise a child. Most women that have their first child substantially younger, are in their early 20s, and don’t go to college. For example in the article “The Age Gap that Women Have Babies: How a Gap Divides America” one of the models shows that unmarried-women without a college degree tend to have their first baby at 23.8 years old. Whereas unmarried-women with a college degree tend to have their first baby at 30.3 years old. Going to college to get a degree can drastically change the age that women have their first baby, if women in areas that have more job opportunities it can make them more inclined to get a college degree which makes the age they have their first child later in their lives. However in Taylor’s County (fictional Pittman County), it is more rural without as many job opportunities for women, therefore many of them just decide not to go to college and raise a kid instead.