- Angwin (125 Companies)
- Annapolis (12 Companies)
- Antelope (521 Companies)
- Antioch (3,555 Companies)
- Anza (99 Companies)
- Apple Valley (2,322 Companies)
- Applegate (37 Companies)
- Aptos (1,396 Companies)
- Arbuckle (94 Companies)
- Arcadia (5,182 Companies)
- Arcata (1,272 Companies)
- Arleta (45 Companies)
- Armona (53 Companies)
- Arnold (243 Companies)
- Aromas (78 Companies)
- Arrowbear Lake (1 Company)
- Arrowbear Lk (1 Company)
- Arrowhead Farms (1 Company)
- Arroyo Grande (2,257 Companies)
- Artesia (1,438 Companies)
- Artois (8 Companies)
- Arvin (408 Companies)
- Atascadero (1,897 Companies)
- Atherton (320 Companies)
- Atwater (1,133 Companies)
- Atwood (8 Companies)
- Auberry (78 Companies)
- Auburn (3,816 Companies)
- Avalon (216 Companies)
- Avenal (187 Companies)
- Avery (23 Companies)
- Avila Beach (68 Companies)
- Azusa (1,770 Companies)
- Badger (11 Companies)