As we saw in the previous map, the U.S. has slightly more female residents than male residents, but not at the extreme rate seen in Russia and other former U.S.S.R. states. So it's not surprising that the majority of the states appear to have ratios below 1.0, where 1.0 represents an even distribution and numbers below that indicate a heavier female population.
What's fun here is that Chase's map also includes age breakdowns inside the visualization. With that feature, you can see that for the age range 21-39, the population is more heavily skewed male, though the southeast and parts of the eastern seaboard still have a higher female population. (You can use those features here.)