One answer (or at least the one we're willing to print) is that they all represent ways in which Americans can spend their time. But which parts of North America are more focused on one or the other? Or, more precisely, where are the resources for each activity more available? Using the number of listings indexed by the Google Maps directory, the map below visualizes the comparative prevalence of churches, bowling alleys, guns and strip clubs across the US (as well as parts of Canada and Mexico). Each point is color coded according to which activity had the most number of hits in the Google Maps directory.
Upon first glance, it is easy to see the relative supremacy of two topics, churches (in blue) and guns (in green), which cover most of the points in North America. Churches dominate throughout most of the southeast and upper midwest (echoing our findings from the virtual bible belt map) while the Northeast, the West and much of Canada show a higher number of listings for guns. One should not, however, interpret this to mean that guns are more prevalent in Canada than the southern U.S. (which clearly does not equate with the offline reality). Instead, the Northeast and Canada have relatively fewer listings for churches than in the south, leading them to be color coded with the next leading activity, i.e., guns. Likewise, there are plenty of gun listings in the southeastern United States, they are simply overshadowed by the listings for churches.
Of more interest are the small pockets in which either bowling alleys or strip clubs are most numerous, bucking the near-universal trend focused on guns and church. For example, there is a prevalence of strip clubs around Las Vegas and Reno, Nevada, as well as Los Angeles, California. Additionally, Canadian cities seem particularly well represented with clusters in Montreal, the Buffalo-Toronto corridor and the Seattle-Vancouver region. Interestingly enough, there seems to be some correspondence (especially in the Northwest US and Toronto) with our map outlining user-generated definitions of fun.
The small pockets of strip clubs around eastern Tennessee along the North Carolina and Georgia borders seem inexplicable, until one considers the advertising landscape along the I-75 corridor, in which religious and pornographic iconography are ubiquitously juxtaposed.
The few areas in which the bowling alleys outnumber churches, guns and strip clubs, are more difficult to explain. There seems to be little rhyme or reason for these bowling hot spots, as they do not correspond well with places with a relative specialization in bowling alleys. The areas shown in red are exclusively rural, so their classification may simply be a result of there not being much else there. Or their residents could really like their bowling. In any case, we plan on contacting Robert Putnam and seeing if he can offer any insight on this.
 Google Maps directories are drawn from a range of sources such as yellow page listings. This category is distinct from and excludes user-generated placemarks used in other maps found on Floatingsheep.