I posted previously about the 2010 bicycle commuting statistics released by the census bureau, which caused one commenter to imply that more dense cities have more bicycle commuting. So I thought I would plug in some surface area numbers, draw some graphs and check some correlations.
The results, if you are like me and want to just skip straight to them, is that I could generally agree with that statement, which surprised me a bit because it seems overly simplistic, but looking at the top 25 US cities by population, sorted by density, it does look like the denser cities have higher rates of bicycle commuting. However, to get there, I kind of had to throw out Seattle and New York. I also added a column for current LAB BFC status, with 5=platinum, 4=gold, 3=silver, 2=bronze, 1=honorable mention, 0=not ranked or I'm not sure). Wasn't sure where I was going with that, actually, but it seemed sort of interesting, and now looking at this chart, I'm thinking Philadelphia really needs to get to work on a BFC application.
| City | Pop | Workers | Cmtr % | # Bike Cmtr | Land Surface Area | Pop Density | Worker Density | BFC Status |
| New York City | 8,184,899 | 3,615,588 | 0.8% | 27,917 | 304.8 | 26853.34 | 11862.17 | 3 |
| San Francisco | 805,463 | 437,814 | 3.5% | 15,208 | 46.87 | 17185.04 | 9341.03 | 4 |
| Washington, DC | 604,453 | 296,717 | 3.1% | 9,288 | 40.1 | 15073.64 | 7399.43 | 3 |
| Boston | 621,383 | 309,620 | 1.4% | 4,369 | 48.4 | 12830.54 | 6393.14 | 3 |
| Chicago | 2,698,831 | 1,168,318 | 1.3% | 15,096 | 227.2 | 11878.66 | 5142.24 | 3 |
| Philadelphia | 1,528,306 | 583,734 | 1.8% | 10,503 | 135.1 | 11312.41 | 4320.75 | 0 |
| Los Angeles | 3,797,144 | 1,706,116 | 0.9% | 16,101 | 468.7 | 8101.96 | 3640.34 | 0 |
| Seattle | 610,710 | 339,160 | 3.6% | 12,306 | 83.9 | 7281.63 | 4043.88 | 4 |
| Baltimore | 620,583 | 256,622 | 0.7% | 1,788 | 92.1 | 6738.14 | 2786.34 | 0 |
| San Jose | 949,197 | 426,136 | 0.6% | 2,708 | 176.5 | 5376.97 | 2413.96 | 0 |
| Detroit | 711,910 | 196,706 | 0.3% | 651 | 138.8 | 5129.03 | 1417.19 | 0 |
| San Diego | 1,311,886 | 620,939 | 1.0% | 6,390 | 325.2 | 4034.21 | 1909.47 | 0 |
| Denver | 604,414 | 296,453 | 2.2% | 6,514 | 153.3 | 3942.69 | 1933.81 | 3 |
| Columbus | 789,939 | 379,334 | 0.7% | 2,498 | 210.3 | 3756.25 | 1803.78 | 0 |
| Houston | 2,107,208 | 961,240 | 0.5% | 4,393 | 579.4 | 3636.88 | 1659.03 | 0 |
| Dallas | 1,202,797 | 543,348 | 0.2% | 820 | 342.5 | 3511.82 | 1586.42 | 0 |
| San Antonio | 1,334,359 | 591,725 | 0.2% | 1,159 | 407.6 | 3273.70 | 1451.73 | 0 |
| Austin | 795,518 | 412,291 | 1.0% | 4,242 | 264.9 | 3003.09 | 1556.40 | 3 |
| Phoenix | 1,449,481 | 620,072 | 0.6% | 3,576 | 516.7 | 2805.27 | 1200.06 | 1 |
| El Paso | 652,113 | 260,318 | 0.1% | 217 | 249.1 | 2618.09 | 1045.12 | 0 |
| Fort Worth | 744,114 | 330,652 | 0.1% | 473 | 292.5 | 2543.98 | 1130.43 | 0 |
| Charlotte | 734,418 | 344,436 | 0.2% | 835 | 297.7 | 2466.97 | 1156.99 | 0 |
| Indianapolis | 824,199 | 366,017 | 0.5% | 1,935 | 365.1 | 2257.46 | 1002.51 | 0 |
| Memphis | 647,870 | 262,033 | 0.1% | 153 | 302.3 | 2143.14 | 866.80 | 0 |
| Jacksonville | 823,316 | 375,579 | 0.2% | 843 | 767.0 | 1073.42 | 489.67 | 0 |
I added the calculated worker density because I thought that might make a difference, in the sense that it should give a better indication of how spread out the people who are commuting to work by bicycle are, and it did make a small difference. New York and Seattle are the outliers though. Actually, Denver is sticking up there about 1.2% or 3000 commuters higher that you would expect, too, but maybe hasn't gone all the way yet, whatever "all the way" may be. Here's my first graph with New York and Seattle included. I did use the spreadsheet's correlation function to calculate a .51 from these numbers, to show you what we get including NYC and STL.

Looking at this graph, I conclude something else besides just population density is going on in New York, and in Seattle going the other direction, to impact bicycle commuting. Also that Denver may be catching whatever it is that Seattle has got. I will go ahead and assume that New York is in transition and also is so big that it's Different, and also that Seattle is being special in its own way (Portland didn't quite make the top 25 by population, or else it would have been up off the top in its own 6% zone saying hey look at me in my tight pants with my excellent coffee and free-range fair trade organic statistics). Removing those two, here's the resulting graph, also switching to workers rather than overall population, which helped a little (correlation now at .87) still with Denver holding out. The two superstars up there that look like they are just about right where they should be for their density are San Francisco and Washington DC.
If you go all the way and take out Denver, it looks even nicer with a .93 but let's not get too carried away. I included the data above because if you actually have read this far and disagree with the overall idea or approach, it is very probable that you know a lot more about this than I do and can straighten me out, so please do. Regarding the original commenter's suggestion about DFW and size and density, there's some different terms that result in different surface areas and densities, from city, to metro, metropolitan area, CSA and MSA, and probably others. The 2010 census bicycle commuting numbers only relate to the city itself, though, and not the larger or different ways of looking at our complex metro landscapes, so I used surface area corresponding to the population number given. For example
one metropolitan area boundary for some Phoenix-related statistics (
mentioned in this post) has it almost the same size as the Netherlands, which is interesting but not used to compile the city-specific bicycle commuting statistics given above. And anyway looking at some of the other MSA boundaries, it's getting harder and harder to tell where one starts and the next stops, but at least on
Wikipedia, DFW is not the largest or most populous or least dense..
And my main conclusion out of all of this is that I am feeling a little cooped up from this cold and need to get back out on the road really soon.