Complex sentence: Popular belief is that the intended name was to be "Yolo" in tribute to Yolo County, California, but that the postal authorities misread the "Y", mistaking it for a "T", thus naming the Post Office "Tolo".
Split into simpler sentences: Popular belief is that the intended name was to be "Yolo" in tribute to Yolo County, California. However, the postal authorities misread the "Y", mistaking it for a "T", thus naming the Post Office "Tolo".