Why is it that all gas stations seem to require your zip code to validate your credit card at the pump?
Requiring me to type my zip code is a poor user experience and extremely poor security. According to the U.S. Census Bureau the United States only has around 40,000 zip codes. Zip codes are not only finite they are trivial to guess. A thief with any intelligence at all will know the relative location he/she accrued the credit card. Narrowing the zip codes to less than 10 because the average American only commutes 16 miles. More than likely the thief will steal the whole wallet or purse and already have the zip code off the ID. A five digit PIN would offer higher security by providing 100,000 possible combinations and making it impossible to guess by geographical location.