The most dismal U.S. states to bike in, if we count simply by the number of women declaring to the census that they use a bike to get to work, are Mississippi, Delaware, West Virginia, Alabama, and Arkansas. Puerto Rico, also surveyed on the question, was similarly quite dismal. Mississippi had just 209 declared female cycling commuters, Delaware just 210, while West Virginia had 326, Alabama had 431, and Arkansas had 461. Puerto Rico declared 318 female cyclists.
The numbers are interesting, but it's important to keep in mind that unlike the regular census, this is a sample, with the possibility of sampling error. If we look at the actual data, the picture is a bit different. Delaware may have just 210 estimated women bicycle commuters, but that number has a margin of error of +/-187, meaning that the number could be as low as 23, or as high as 397. Keep this in mind when you're reading the rest of these figures.
The absolute numbers also tell only part of the story. If Delaware has only 210 women bicycle commuters, it also only has 873,092 people, 201,587 of whom are female commuters. It's the proportion of bicycle commuters among all female commuters that is really comparable from one state to another. If we consider Delaware's 0.10% figure (that's a tenth of one percent), the state rises from second lowest to ninth lowest, and Alabama (0.044%) drops from fifth lowest to second lowest.
In terms of proportion of women commuting by bicycle, the worst states are actually Mississippi (0.036%), Alabama, Tennessee (0.047%), Missouri (0.071%) and Arkansas (0.075%) - pretty much an Ozark-Delta-Appalachian belt of nastiness towards female cyclists. The best state by that measure is Oregon, with 1.4% of women commuting by bike. The next is D.C. (1.2%) and then a Rocky Mountain belt with Hawaii thrown in. So we know it's not the mountains.
In the Treehugger post, blogger April Streeter observes that 41% of all bike commuters in Rhode Island are women. That's an interesting number, but instead of the simple percentage of all cyclist commuters, a better estimate of the relative popularity of bike commuting between genders is the ratio of the proportions of bike commuters out of all commuters in each gender. Rhode Island's ratio is in fact high: 0.74% of women ride bikes to work for every 1% of men doing it. However, Vermont (0.86) and Utah (0.85) are even better. New England seems to be a good place for gender equality in bike commuting: both New Hampshire and Maine had 0.72% of women per 1% of men. Massachusetts (0.46) doesn't do as well, though, and neither does Connecticut (0.34) or New York (0.37).
The worst female-male ratios included most of our Graceland belt, with the worst in the country being - yup - Mississippi with only 0.08% of female bike commuters per 1% of males. Arkansas breaks from the belt with 0.43, but joining the bottom five are Puerto Rico (0.12) and Nevada (0.15). Tennessee had 0.18, Missouri 0.21 and Alabama 0.22 - but our friend Delaware is tied with Alabama.