There are more women and U.S. citizens in Napa's vineyards than you probably thought.

With immigration continuing to be a hot-button issue in the United States, the Napa Valley Grapegrowers (NVGG) stepped forward last week to try to correct myths about farmworkers.

It is a striking fact that the overwhelming majority of the men and women who tend grapevines in California's most famous wine region are of Mexican origin. 

However, the NVGG says it's a myth that most Napa Valley farmworkers are illegal immigrants. 
"We have a really strong citizenship program in Napa," Jennifer Putnam, CEO of Napa Valley Grapegrowers, told Wine Searcher.

Putnam could not estimate what percentage of Napa farmworkers are citizens. However, NVGG does report that 20 percent of farmworkers are women, busting the myth that it's a man's job.

Putnam adds that "farmworker" is too general a word for Napa Valley. While an entry-level vineyard worker might make only $12 an hour, a supervisor with English-language skills might make $24 an hour, and somebody with mechanical certification, such as driving specialized vehicles, might make $40 an hour.

A 2011 survey showed that 55 percent of Napa vineyard workers were offered 401K plans (employer-sponsored tax-sheltered retirement savings accounts).

Napa County also runs farmworker housing centers, a boon to workers on the entry-level wage in a county where housing is both rare ande expensive.

"The occupancy rate is 95 to 100 percent," Putnam said. "The word is out. The centers are great places, they're very clean. There's meals, there's recreation."