American and US Airways completed their merger last month and one of the milestones was reciprocal mileage benefits by January 7th, 2014. At the moment, you can use American Airlines miles for US Airways flights (conversely, you should be able to use US Airways miles for American flights).
Doing a quick search for a simple flight between New York – LaGuardia and DC – Reagan National, we found you can book US Airways flights using American miles. For short distance flights, unless you have an immediate need, we recommend you wait until US Airways enter the Oneworld alliance and use British Airways Avios on March 31st. Short distance flights using BA Avios is significantly cheaper than American miles.
Read more:
http://www.theflightdeal.com/2014/01/07/airways-awards-american-airlines-miles-live/#ixzz2ph1vT5CP