Every year, family stability gets covered as one national headline, the marriage rate is up, the marriage rate is down, birth rates are falling. That framing hides more than it reveals, because the real story has always been regional. The Institute for Family Studies’ 2026 Family Structure Index finally breaks it down state by state, and the gap between the top and bottom of the ranking is wide enough to change how you think about where family stability is actually happening in America.
How the index actually works
The Family Structure Index combines three measures: the share of adults ages 25-54 who are married, the share of teenagers living with married parents, and the total fertility rate in each state, all benchmarked against a baseline score of 100 set at year 2000 levels using 2022-2024 data. A state scoring above 100 means family structure indicators have actually strengthened since 2000. A state well below it means the opposite. Almost every state falls short of that 2000 benchmark, except one.
Utah stands alone at the top
Utah is the only state in the country scoring above the 2000 baseline, landing at roughly 103. It leads on all three underlying metrics simultaneously: the highest share of married prime-age adults, the highest share of teens living in married-parent homes, and the sixth-highest total fertility rate in the nation. Idaho and Nebraska round out the top three, and South Dakota, notably the only state in the entire country with a total fertility rate above 2.0 right now, lands in the top four as well. There’s a clear regional pattern here: the top of the index is dominated by states in the Mountain West and Great Plains.
New Mexico anchors the bottom, and the spread is stark
At the other end sits New Mexico, ranked 50th, with a composite score around 78.4, married-adult share at 46.9%, teens with married parents at just 52.5%, and a fertility rate of 1.59. Rhode Island and Louisiana round out the bottom three. Do the math and the gap between Utah at the top and New Mexico at the bottom comes out to roughly a 24-point spread on the index, a difference the report attributes to a mix of lower religious attendance, more family instability, lower educational attainment, and, in some states, elevated housing costs.
The religion and housing numbers are doing a lot of the work
Two variables explain an outsized share of why some states cluster at the top and others at the bottom. Religious attendance alone explains 57% of the variance in state-level fertility rates, according to the report, while housing affordability explains another 25% of that variance. That’s not a small correlation, together, those two factors account for the overwhelming majority of why fertility rates differ from state to state, which suggests the “family formation crisis” conversation happening nationally is really two more specific, more solvable conversations: one about religious community and one about the cost of a house.
People are voting with moving trucks
Maybe the most concrete evidence that these state-level gaps are being felt in real time: from 2019 to 2024, married adults as a share of the population increased by 1.8 percentage points in red states while declining in blue states over the same period, and roughly 370,000 families relocated from blue states to red states during that five-year window. Whether that migration is driven by housing costs, family policy, cultural fit, or some combination of all three, it lines up with exactly the kind of regional divergence the Family Structure Index is designed to measure.
What the map actually tells you
The national trend line was never wrong, exactly, it just averaged away the fact that family stability looks completely different depending on which state you’re standing in. A 24-point gap between the best- and worst-performing states isn’t a rounding error; it’s evidence that policy, cost of living, and community structure are producing genuinely different family outcomes across the same country, in the same decade, under the same national economy.
