Note 410 — Chapter X · THE TRUNK LINE RATE SYSTEM: A DISTANCE TARIFF
Reading edition
Thus from Ironton, in the 87 per cent. zone south of Columbus, Ohio, the distance to Columbus is 127 miles, added to 638 miles from Columbus to New York makes a total of 765 miles. Multiplying this by 00.0206 makes it 87 per cent. of the Chicago rate.