http://www.kauffman.org/research-and-policy/mit-entrepreneurs.aspx

Main highlights are:

The overall MIT entrepreneurial environment, consisting of multiple education, research and social network institutions, contributes to this outstanding and growing entrepreneurial output. Highlights of the findings include:

• An estimated 6,900 MIT alumni companies with worldwide sales of approximately $164 billion are located in Massachusetts alone and represent 26 percent of the sales of all Massachusetts companies.
• 4,100 MIT alumni-founded firms are based in California, and generate an estimated $134 billion in worldwide sales.
• States currently benefiting most from jobs created by MIT alumni companies are Massachusetts (estimated at just under one million jobs worldwide); California (estimated at 526,000 jobs), New York (estimated at 231,000 jobs), Texas (estimated at 184,000) and Virginia (estimated at 136,000).