I've been interested in creating a methodology for identifying where people skateboard in their neighbourhoods and around their cities. Of course the challenging part of this is that it the presence of someone skateboarding is ephemeral. You only really know someone is doing it if witness them. The other options for understanding where and people skate and have been skating in recent years is changes to the built invironment (the creation of a park, the linear scraping of paint, the compressed shine of a wood, the removal of caps, or the addition of wax to certain surfaces).
Skate wax is something I find perticularly interesting because it is often applied to concrete surfaces, like curbs. In the city and suburbs of the west, the land where the car truely rules, conrete curbs are everywhere. Previously in some cities, curbs wheere made from painted granite. A city couldn't formulate a better low ledge for a skateboarder today. Granite is hard, dense, and smooth, the thick paint would add even more slickness. Now concreate curbs are extruded, and highly textured, but still everywhere. To grind a low textured ledge, skate wax is added to smooth out the surface and allow the deck or trucks to glide more easily. Aften "skate wax" is only a product sold, and it's a lot more commen to see a dollar store parafin candle passed around for curbs, ledges and rails.
Skate wax is easy to spot once you know what you're looking for. It can be a dirty, grey sheen, coming off the concrete, or cinnamon scented sticky red layer on a rail. Was is interesting because it is not as ephemeral as a skateboarder, but respondes to weather and time, coming away, or continually built up by years of skaters at a specific spot.