For 2012 and forward, all Offroad National Championships will be online registration only. Registration for these events will open approx 4 weeks before the event and close approx 1 week before the event in order to determine what categories qualify for Champs status (based upon a criteria of a minimum of 5 riders per category)
If you do not register online, you will be unable to enter the events.
For the XC & DH NPS (National Points Series) , you must use online reg. when it is provided.
A link to the various registration forms will be provided in the race promotion post for each race, you may also try the links per below:
Below are reports showing who has registered for the various offroad events
List of registered riders for the 2013 XC NATIONALS (Carn Wheelers) is HERE