From a report in The New York Times:
Generally, men and women in the Northeast marry later than those in the Midwest, West or South. In New York, New Jersey, Connecticut and Massachusetts, for example, the median age of first marriage is about 29 for men and 26 or 27 for women, about four years later than in Arkansas, Idaho, Kentucky, Oklahoma and Utah. And tracking the red state-blue state divide, those in California, Illinois, Michigan, Minnesota and Wisconsin follow the Northeast patterns, not those of their region.
…Generally, the study found, states in the Northeast and the West had a higher percentage of unmarried-partner households than those in the South, In Maine, New Hampshire and Vermont, unmarried couples made up more than 7 percent of all coupled households, about the twice the proportion of such households in Alabama, Arkansas and Mississippi.
On teenage births, the same differences become clear. In New York, New Jersey and Massachusetts, about 5 percent of babies are born to teenage mothers, while in Arkansas, Georgia, Louisiana, Mississippi, Montana, New Mexico, South Carolina, Texas and Wyoming, 10 percent or more of all births are to teenage mothers.