Online storefronts like eBay have enabled more Americans to go into business for themselves, according to new Census Bureau statistics.

The number of self-employed Americans grew by 1 million, to 19.5 million, between 2003 and 2004. While that represents an increase of roughly 4.7%, the number of electronic shopping and mail-order businesses run by sole proprietors increased by 12.7% over the same period.

"Our merchant base is mostly sole proprietors," said Amanda Pires, spokeswoman for PayPal, an eBay-owned site that allows individuals and companies to accept and send credit card payments online.

"An individual working alone can create a global businesses using eBay," Pires added. "Sellers can turn over their inventory much faster. They get their money instantly so they can send goods immediately. They no longer have to wait to receive a check and the check to clear before they send their goods."

Online retail was not the only category to post significant gains, however. Other sectors experiencing an increase in self-employment ventures included building finishing contractors (up 22.5%), Internet service providers (up 18.7%) and nail salons (up 14.7%).

Currently, sole proprietorships account for 70% of all U.S. businesses and generate $887 billion in annual sales.