http://www.google.com/trends?q=parkour,+freerunning,+&ctab=0&geo=us&geor=all&date=all&sort=0Huh...
Top states in the USA that searched "parkour":
1. Utah, United States
2. Oregon, United States
3. Washington, United States
4. Colorado, United States
5. Hawaii, United States
6. Virginia, United States
7. California, United States
8. Indiana, United States
9. Connecticut, United States
10. Arizona, United States
Utah, Washington, Colorado, Hawaii, Virginia, and California as I understand it has quite big and "notable" communities. (Not that others don't.)
Top cities in the USA that searched for "parkour":
1. Salt Lake City, UT, USA
2. Milpitas, CA, USA
3. Sterling, VA, USA
4. Portland, OR, USA
5. Denver, CO, USA
6. Seattle, WA, USA
7. Pleasanton, CA, USA
8. San Francisco, CA, USA
9. Rochester, NY, USA
10. Raleigh, NC, USA
Very similar. Utah, California, Virignia, Oregon, and Colorado all prevalent.
Just thought I'd share this with y'all.
EDIT: Grammar changes