Here is the chart:
Perhaps surprisingly, it varies quite a bit from section to section. Hawaii has the most men at 62% while New England has the most women at 69%. Northern Cal and the Caribbean have high percentages of men too while the Southern section has a large percentage of women.
Is there an "equal opportunity" section that is 50/50? It appears not, with the Pacific Northwest being the closest at 49% men and 51% women and Texas next at 48%/52%.
Now, I don't have absolutely every USTA match played in 2013 in my database, but I have a large enough sample (thousands of players in each section) that they are representative.