Fifth Avenue roughly bisects Manhattan Island and acts as the demarcation line for east/west designations (e.g., East 27th Street, West 42nd Street); street addresses start at Fifth Avenue and increase heading away from Fifth Avenue, at a rate of 100 per block on most streets. South of Waverly Place, Fifth Avenue terminates and Broadway becomes the east/west demarcation line. Although the grid does start with 1st Street, just north of Houston Street (the southernmost street divided in west and east portions; pronounced HOW-stin), the grid does not fully take hold until north of 14th Street, where nearly all east-west streets are numerically identified, which increase from south to north to 220th Street, the highest numbered street on the island. Streets in Midtown are usually one-way, with the few exceptions generally being the busiest cross-town thoroughfares (14th, 23rd, 34th, and 42nd Streets, for example), which are bidirectional across the width of Manhattan Island. The rule of thumb is that odd-numbered streets run west, while even-numbered streets run east.