The 2017 USA Rulebook Amendments describes the set of rules to be used for American unicycling competitions. The 2017 Rulebook Amendments cannot be used as an independent document; they must be used in conjunction with the 2017 IUF Rulebook. This document describes where the Unicycling Society of America chooses to differ from the IUF Rulebook for their competitions.
A mirror of the 2017 IUF Rulebook can be found here (in case of issues with the link above).
In particular, the rulebook outlines rules for NAUCC competitions.