All Dallas ZIP codes begin with the number seven because it is the primary prefix assigned by the U.S. Postal Service to the states of Texas, Oklahoma, Louisiana and Arkansas. The next number of the Dallas area ZIP codes is a five followed by either two or three, representing a sectional mail processing and distribution center within the metropolitan region. The last two ZIP code digits are further broken down by address groups and mail delivery rather than by geographic areas. As a result, there may be some overlap of ZIP codes in a particular area. The last ZIP codes in each sectional distribution region are 75295 and 75398.
The ZIP code system began in 1943 when the U.S. Postal Service started postal zones in large cities because increased population and a larger number of buildings made mail delivery more complex. By 1963, five-digit ZIP codes were introduced nationwide, and in 1967, the codes were mandatory for second and third-class bulk mail. The system was gradually implemented to include all mail delivery. In 1983, an additional four-digit code was added, but due to public resistance, this code isn't required as of 2015.Learn more about Postal Services