How did the bus routes get their numbers? Some of the numbers seem to make sense and some do not. For example, 72 North Ave, 73 Armitage, 74 Fullerton - the numbers are going up and 74 is north of 73 and 73 north of 72. But Diversey (the street north of Fullerton) is not 75, it is 76. Why is there the jump in numbers?