On your graph, California has the 5th highest birth rate at 1.95. A lot of Freepers comment negatively in regards to California, wishing it would drop into the sea, accusing it of being mostly nuts and gays. Nothing could be further from the truth. Lots of normal people in California, meaning conservative heterosexual family types, and they are having lots of children. I see lots of baby strollers and children here in the SF Bay Area, there are even lots of them in San Francisco. How does one explain that there are fewer kids being born in flyover states (with the exception of a few like Utah)?
People in red states understand what it takes to live within their means. California just breeds dreamers that understand what it takes to live off other people's means.
Welfare states have mitigated the consequences of having more children than a person can afford. In fact, lifetime recipients of welfare often have figured out how to game the system to maximize their opportunities in the system, including popping children out like rabbits.
Flyover states aren't doing as well economically due to the decline of manufacturing in America. SF Bay Area is benefiting from the tech boom, and Utah, well, Mormons tend to be well educated and entrepreneurial.