The economic downturn crushed the dreams of thousands of entrepreneurs.

More than 170,000 small businesses in the U.S. closed between 2008 and 2010, according to analysis by the Business Journals of U.S. Census Bureau data.

There were 6.79 million small businesses in the U.S. in 2010, down from 6.96 million in 2008, according to the Business Journals. 2010 is the most recent year for which official data has become available. You can find out how many small businesses shut down in your area between 2009 and 2010 in the Business Journals' database here.

Entrepreneurship plunged during the recession. The number of self-employed Americans fell 4 percent to 9.8 million between November 2007 and June 2009, according to U.S. Census Bureau data cited by the Federal Reserve Bank of Cleveland. Twelve percent more businesses shut down in 2009 than in 2007.

Many who were laid off during the recession started small businesses because they had no other choice. Eighteen percent of entrepreneurs that launched their own business in the last 12 months have done so after losing their jobs, which is double the rate before the recession, according to a recent poll by WaveAccounting.

But many of these small businesses are not exactly thriving. Nearly four in five businesses have no employees at all, and they make an average $45,000 per year, according to the U.S. Census Bureau. Meanwhile, the share of new startups that employ workers continues to fall, according to the Kauffman Index of Entrepreneurial Activity.

As James Ledbetter, op-ed editor at Reuters, tweeted in June: "Small businesses 'create' majority of jobs. As in: when Reuters fires me, I will become a small business. Job created!"