The recent trend has been to name most ships and subs after cities or states, presumably to touch a chord with as many citizens as possible for budgetary reasons.

They have also named a few ships after favored politicians or famous service members. John Stennis was a big navy proponent in congress.

Carter probably got the nod because he was one of the first nuclear submariners, as well as the first annapolis grad to become president.

Presumably we will not see a USS Clinton