If you currently live in the USA, you can make a donation, with all the eligible tax advantages, through US Friends of Royal Ottawa Foundation Inc.:
US Friends of Royal Ottawa Foundation
1145 Carling Avenue
Ottawa, ON., K1Z 7K4
Attention: Janie Scully
For more information on giving from the USA, please contact Janie Scully at Janie.Scully@theroyal.ca