Aha, I did not realise that. How interesting. Thanks!
The values on that map are a little frustrating, have we got anything which offers more precision for those enormous 1-91 and 108-205 ranges? I look at that and think "Across the country the ratio could only vary between about 9 men for every 10 women and 9 women for every 10 men and the diagram would still be totally correct - is that even really significant?".
("Is that even really significant?" is a whole other question that I'm sure someone can easily answer. I don't have any intuition about how skewed a gender ratio has to be for it to be noticeable to a member of that population, certainly if someone told me that there were only 9 women for every 10 men in a city I wouldn't immediately think my chances of hooking up would be hurt too much...would they?)
I think that the places covered by those enormous ranges can be fairly comfortably assumed to almost all be close to 91 and 108.
As for a 9:10 ratio, it all depends on the rate of committed relationships. Remember that this is all people, married, committed, and single. If they're all single, 9:10 is probably pretty good. If 95% of people are in a committed relationship (ignoring homosexuality, which probably cancels out) then you have no hope at all. If we pick a more sane number like, say, 75% (not sure how sane, but...) then that results in about the singles scene having about a 2:3 ratio, which is not so great for the people on the 3 side.
According to the statistics site that the OP used, 54 million Americans are single. [1] Ignoring the 62 million Americans that are under fifteen, we find that only 21% of American adults are available. [2] So if your area's ratio is 9:10 and ~80% of the people are taken, you end up with a 7:12 ratio among the singles (ignoring homosexuality).
The values on that map are a little frustrating, have we got anything which offers more precision for those enormous 1-91 and 108-205 ranges? I look at that and think "Across the country the ratio could only vary between about 9 men for every 10 women and 9 women for every 10 men and the diagram would still be totally correct - is that even really significant?".
("Is that even really significant?" is a whole other question that I'm sure someone can easily answer. I don't have any intuition about how skewed a gender ratio has to be for it to be noticeable to a member of that population, certainly if someone told me that there were only 9 women for every 10 men in a city I wouldn't immediately think my chances of hooking up would be hurt too much...would they?)