The Bureau of Labor Statistics points out that the following states have the highest numbers of tech writers: Washington, DC, Massachusetts, and California. But, while contemplating a tech writing career, you should also remember that many other types of businesses, like publishing companies, hire tech writers, and you could work anywhere in the U.S., including right from home.
A glimpse at Monster.com’s online job postings give you an idea of the types of companies in California that are currently in search of tech writers:
Bureau of Labor Statistics. "Technical Writers." Occupational Outlook Handbook, 17 Dec. 2009. Web. <http://www.bls.gov/oco/ocos319.htm>.