It's not too surprising that people are generally waiting to have kids later in life. But still a very interesting analysis of 4 decades of birth in America and how socioeconomic and geographical factors play into it. With lots of good data to look up based on county, age, etc.

Some quotes I found interesting:

"Lower-socioeconomic-status people might not have as many opportunity costs — and motherhood has these benefits of emotional fulfillment, status in their community and a path to becoming an adult."

"But if going to college and achieving an upper-middle-class lifestyle seems unattainable, then having a family might seem like the most accessible source of meaning to you.”