The system of naming streets shall be as follows: the streets or highways running north or south shall be known as "streets" and named by numbers, beginning with Sixth Street near city east town line and continuing westward to Thirty-fourth Street at the western limits of the city, and so on to apply to such additional streets or extended limits of the city hereafter. Additional streets laid out eastward from said Sixth Street in any additions to the city shall be numbered likewise to First Street, and thereafter eastward alphabetically beginning with `A' street, provided that all such streets crossing Broadway westward as far as Nineteenth Street, and those crossing Western Avenue from Nineteenth Street, west to the city limits may be divided into `north' and `south' streets by Broadway or Western Avenue for the purpose of more definitely locating street numbers relating to buildings thereon. The streets or highways running east and west shall be known as "avenues," except Broadway, by their names as shown on the official maps of the city unless changed by ordinance.
('68 Code, § 6.03)