Airships of the line.
The USCG has 10 Levs in service they are as follows: Vigialant (lead ship in class), Active,General Green,Massachusetts,Scammel,Argus,Virginia,Diligence,South Carolina, Eagle. Five of these are based on the eastern seaboard, four on the pacific coast and one in the great lakes. (Alaska and Hawaii are still territories at this point so they get standard 'wet' coverage and the Navy probably has at least a patrol group that covers both areas.)