Top 10 startup cities

1. Boulder

2. Fort Collins

3. San Jose-Sunnyvale-Santa Clara, Calif.

4. Cambridge-Newton-Framingham, Mass.

5. Seattle, Wash.

6. Denver

7. San Francisco, Calif.

8. Washington-Arlington-Alexandria, DC-Va.-Md.

9. Colorado Springs

10. Cheyenne, Wyo.

Boulder is the top city for tech startups in the U.S, according to a joint report released today by research foundation Engine and the Missouri-based Ewing Marion Kauffman Foundation.

The report measured the density of tech startups -- companies between 1 and 5 years old -- and found that after adjusting for city size, Boulder had a tech startup formation rate six times the national average.

"In the case of Boulder, a startup community whose evolution I've observed and participated in closely over the past many years, the cultural and economic transformation has been extraordinary," Brad Feld, co-founder of Boulder's Foundry Group and the Boulder-based startup accellerator TechStars, said in the report. 

"While there isn't one, definitive blueprint to building a technology industry, this research can hopefully inspire communities and policymakers to work together to ensure that the spread of high-tech entrepreneurship isn't just a trend, but a long-term phenomenon."

Boulder was one of four Colorado cities to place in the Top 10 in the report. Fort Collins came in second, Denver came in sixth and Colorado Springs came in ninth.