SMC 11.40.160 Crossing intersection diagonally - Seattle Municipal Code

No pedestrian shall cross a roadway intersection diagonally unless authorized by official traffic-control devices; and, when authorized to cross diagonally, pedestrians shall cross only in accordance with the official traffic-control devices pertaining to such crossing movements. (RCW 46.61.240(4))
(Ord. 108200 Section 2(11.40.160), 1979.)