Page 603 of Walter Romig's Michigan Place Names says:
Whittaker, Washtenaw County:
Frank Whittaker opened a general store here about 1860 and the village was named for him; given a station on the Wabash Railroad in 1880 and a post office on Jan. 9, 1882, with William H. Bishop as its first postmaster [France Sikorski, PM; PO Archives]."