The top 10 cities for tech:
1. San Francisco area (Apple, Facebook, Google, Twitter) Number of start-ups: 3,442. $11.8 billion invested in 2011 for 430 companies.
2. Boston (TripAdvisor, Kayak, Carbonite) Number of start-ups: 700. $2.77 billion invested in 2011 for 285 companies.
3. New York (Foursquare, Tumblr, Fab.com) Number of start-ups: 1,844. $2.73 billion invested in 2011 for 332 companies.
4. Los Angeles area (Demand Media, Break Media, Citysearch, Electronic Arts, Viddy) Number of start-ups: 1,507. $2 billion invested in 2011 for 129 companies.
5. Washington, DC: (Living Social) Number of start-ups: 261. $979 million invested in 2011 for 146 companies.
6. San Diego (Qualcomm, Slacker) Number of start-ups: 329. $915 million invested in 2011 for 89 companies.
7. Chicago (Groupon, Orbitz, Motorola) Number of start-ups: 556. $750 million invested in 2011 for 79 companies.
8. Austin (Dell, Photodex, Bedandbreakfast.com) Number of start-ups: 487. $646 million invested in 2011 for 70 companies.
9. Boulder/Denver (Mapquest, Photobucket) Number of start-ups: 395. $584.6 million invested in 2011 for 85 companies.
10. Seattle (Microsoft, Amazon, Zillow, T-Mobile.) Number of start-ups: 441. $580 million invested in 2011 for 96 companies.
Source: National Venture Capital Association, Angellist.com