OMRA (oregon motorcycle riders association) has added an ATV segment to thier organization. the details can be found here:
http://omra-online.org/2004/latestnews_2_2004.htm

the main purpose is unification of groups that use the same resources for representation.

there will be a pilot mini XC/GP series this fall and a 10-14 race ATV series for 2005. details, classes, rules, etc. are currently being worked on.