Green’s Dictionary of Slang

shorts, the n.³

In phrases

tread the shorts (v.) [i.e the short distances of a few blocks]

(US black) to stroll or promenade.

1936

D. Burley in Chicago Defender 7 Nov. 6: They do have ‘barking Fidos’ which yelp in pain and anguish as their owners ‘tread the shorts’ seeking fun, ‘flames’ and fortune.