Well according to Claudia De Lys writer of the book 8414 strange and fascinating superstitions the number thirteen has a rather distinct place in american money.
Americans unwittingly carry the unlucky number when they carry a dollar around. The design on the back of this bill bridges ancient Egyptian allegorical motifs to our own times,as symbolic uses of the number thirteen have been arranged around each of the two sides of the Great Seal of the United States. Among them, for example, is an incomplete or truncated pyramid of thirteen steps. There are thirteen leaves and berries on an olive branch, and in the left talon of the american bald eagle are thirteen arrows.
The many uses of the number thirteen in the design refer to the thirteen original colonies.
It was the ancient hindus who are reputed to have started the superstition that thirteen people squatted together was unlucky. The scandanavians tell the story in more detail. The legend goes that loki, the principle of evil, though uninvited, joined the twelve demi-gods at a feast. He had instructed Hodur, the blind one, symbol of darkness and night, to shoot baldur, the bright one, symbol of the sun, with an arrow of mistletoe. Hencefort, thirteen at a table became taboo.
For the egyptians however, they regarded the number 13 as lucky. It represented the final step or stage of earthly existance, in which one was merged into permanence or spiritual transformation. They were the first ones to discover that there are 13 moons in a year, and gave a name for each one, like harvest moon, fruit moon etc...