Cambial electrical resistance (CER) was assessed over a year-long period, using the Shigometer, for 109 sweetgum trees (Liquidambarstyraciflua) planted along streets in Seattle, Washington. CER decreased through the spring, reached a minimum in summer, increased through the fall and was maximal in mid-winter. The seasonal maximum was 200-600% greater than the summer minimum. CER measurements could not be related to growth parameters such as seasonal shoot increment and diameter growth.