Are entrepreneurs better suited to become Commander-in Chief? Maybe, or maybe not, but the fact remains that many of the most famous presidents in history ran their own businesses before they ran the country.

Presidents have long touted the benefits of supporting small businesses, so in honor of President’s Day, here are some of the country’s most dynamic small business owners and entrepreneurs.

Abraham Lincoln

(Served 1861–1865)

The Kentucky-born lawyer is probably best remembered for ending slavery – not to mention his facial hair – but he also happens to be the only president to hold a patent. The historic president’s patent no. 6,469 was a mechanical device designed to lift boats over sandbars or other obstructions by attaching inflatable bellows that would expand when necessary, although it was never manufactured.

Lincoln came by his obsession with mechanical devices honestly. He “evinced a decided bent toward machinery or mechanical appliances, a trait he doubtless inherited from his father who was also something of a mechanic,” said his law partner William H. Herndon.

Aside from his entrepreneurial endeavors, Lincoln also opened and ran his own successful law firm before becoming president in 1861.

Warren G. Harding

(Served 1921–1923)

The oft-overlooked Republican has gained notoriety in recent years for his womanizing ways, especially after the Library of Congress shared a series of steamy love letters written by the president to his mistress Carrie Fulton Phillips.

Harding’s personal life may have recently set tongues wagging, but it’s his entrepreneurial spirit that turned heads some 130 years ago. When he was just 19, the entrepreneur (alongside other partners) purchased the struggling Marion Star newspaper in Ohio and instituted himself as the publisher. Under his leadership, the publication’s circulation increased and the paper turned into a profitable endeavor that helped fund his presidential ambitions.

Franklin Roosevelt

(Served 1933 to 1945)

It’s a well-known fact that FDR suffered from polio for most of his adult life. And while he wasn’t an entrepreneur in the traditional sense, he certainly had the entrepreneurial spirit when it came to creating institutions to help others who suffered from the crippling disease that relegated him to a wheelchair.

Attempting to rebuild the economy in the wake of the Great Depression by passing the New Deal and fighting World War II certainly took up a great deal of Roosevelt’s time in the White House. But the only president to be elected four times also found time to establish the Georgia Warm Springs Foundation(now the Roosevelt Warm Springs Institute) to treat others suffering from polio and launched the March of Dimes (originally known as the National Foundation for Infantile Paralysis) to help fund research and education about the disease.

The Warm Springs is still in operation and acts a vocational training agency and rehabilitation center for people with disabilities. Meanwhile, after a polio vaccine was discovered in 1955 the March of Dimes decided to focus its resources on improving the lives of mothers and babies through various health campaigns, which includes raising awareness about premature births.

Harry Truman

(Served 1945–1953)

Not every entrepreneur needs to finish college (or even start it) in order to accomplish big things in life. Mark Zuckerberg, Steve Jobs and Bill Gates have all proven that success can happen with or without a college degree.

America’s 33rd president is simply one more in a long list of successful entrepreneurs who opted out of a college degree – in his case, that was due to financial difficulties rather than choice. Truman attended Spalding’s Commercial College, but left after only one semester in order to earn more money. Between 1919 and 1922, he ran a clothing store in Kansas City with friend and one-time business partner Eddie Jacobson. The store nearly went bankrupt during the recession that followed World War I, but through sheer determination and grit, Truman managed to pay off the store’s debt before becoming president.