FLY777UAL is right, Nashville and Raleigh were both cut as being hubs for American. I personally believe that AA was wrong to cut Nashville hub, but there were other issues that prevailed from my understanding.
The current cities that are classifies as hubs are:
DFW, ORD, MIA and SJU (to a lesser extent).
I would not consider JFK a hub even though it is one for American Eagle. Basically the flights in and out of JFK are international, international feeders on Eagle and transcontinental flights (LGA has a perimeter rule which makes transcontinental flights not possible).
BOS is a city that AA has recently focused on and has/is investing a lot of money into building. For example, look at the purchase of the American Connection on Business Express. However, I do not consider BOS a hub since flights in and out are not structured that way from what I can tell. New service to Nashville (Eagle) has been announced but from what I see, BOS is still a point to point type of city.
SJC is no longer a hub either. It was cut earlier in the 90's as well. However, with the purchase of Reno Air, American has really increased their presence again. Of course there is no Eagle feed into SJC either and the flight structure in SJC is not really one of a hub as well. However there is the Tokyo flight there which seems to have several west coast connections to and from it. But, if you are going to classify SJC as a min-hub, you might as well classify RNO and LAS as ones too. AA flies about 35 daily flights out of RNO and about the same out of LAS which is in line with SJC.
If anything was to be classified as an American hub on the west coast, I would call LAX one. LAX has not been classified as a hub by AA (UA has), but AA probably has about 185 flights (not including AE) that connect the west coast and transcontinental flying as well as important cities like Austin, Houston, Fort Lauderdaule, Orlando, Honolulu, Maui, Gudalahara, Paris and London. American Eagle also has a hub there that serves as a feeder service as well from San Diego, Bakersfield, Fresno, Palm Springs and Santa Barbara to name a few