The fastest growing industries in the Los Angeles county are listed here. The quickly expanding industries in the LA county are fast becoming major sectors not only in LA but also throughout the country. If you want to set up a new business around LA, this list suggests the best industry to invest in right now. These expanding businesses are listed by job growth and fastest growing business opportunities. LA is often considered the pulse of where the nation is heading and this is the list of the fastest growing business sectors in the county of Los Angeles from 2001-2008.