I have seen this one before too... for OHIO.
For Washington State, I always signed Washington State. and Washington DC as Washington D.C.
Some states I don't know signs for, I tend to fingerspell the abbreviations. Like RI for Rhode Island, MD for Maryland, etc...
Other state signs that I know of...
MAINE = almost like Pittsburgh, but opposite motion?
MASSACHUSETTS = 1) sign "fed up" or 2) fingerspell MASS
FLORIDA = fingerspell FLA or use "F" and move from head to down
GEORGIA = sign like Washington, but use G, or fingerspell GA
MISSISSIPPI = sign "miss" (as in I miss you) with "I" up too
PENNSYLVANIA = fingerspell PA or (bad sign ... PENIS STUPID LOL, we New Jerseyans are very happy about the shore traffic from PA hee hee)
VIRGINIA = fingerspell VA or same idea about PA, bad sign but use V on nose then STUPID
LOUISANA = fingerspell LA or sign "SHIT" with L shape then when move down, change to A handshape (oops)
Thats really all the signs I know, except for the West Coast states already mentioned here. The rest, I just fingerspell. WOuld be interesting to see how everyone sign their states. Hope you dont get mad at me for saying bad signs too LOL