To participate in this year’s 2019 National tournament (November 2-10, 2019) a player must have participated in at least one qualifying event between July 16, 2018, and July 15, 2019. It is not necessary to have participated in one-for-one events. For example, if you played mixed in a sanctioned tournament, you are eligible to participate in singles, doubles, and mixed doubles.
If a player does not live in the US for more than 3 months a year and is not able to participate in a USAPA sanctioned tournament, he/she may request a hardship exemption from the Tournament Director. Like all participants, international players are still required to have a valid USAPA membership through the duration of the National Championships.
More information here.