07/19/2012 10:14 am ET Updated Jul 19, 2012

8 U.S. Presidents Who Ran Their Own Businesses (PHOTOS)

Mitt Romney has said more than once that his private sector experience will help him reinvigorate America's stagnant economy.

The Republican nominee is so adamant about business acumen as a prerequisite to the presidency that he has pitched a constitutional amendment that would require presidents to have spent at least three years working at a for-profit company. But is business experience really an indication of presidential prowess?

Scott Shane, a professor of entrepreneurship at Case Western University, recently tried to answer that question in an Entrepreneur magazine column. Shane identified presidents with business experience and noted where they stacked up in a survey of 238 presidential scholars ranking the best and worst commanders in chief.

Six of the 10 "best" presidents had business experience, albeit some notable failures. One POTUS owned a general store, another started a clothing shop, but both businesses ultimately went bankrupt. Meanwhile, some of the "worst" presidents hit entrepreneurial home-runs, including a highly profitable newspaper and a family peanut farm that expanded into an international business.

"Among those presidents with business experience, the successful ones don’t appear to be better at running the U.S. than unsuccessful ones," Shane concluded.

To shed some more light on the issue, we've compiled the full list of past presidents who ran their own ventures. Do you think business experience should be a prerequisite for future presidents?