When Fred McCrea and Cesare Mondavi left Minnesota in the first half of the 20th century, little did they know they'd be spawning wine legacies that would span generations to come.

Today, their grandchildren are embedded at iconic Napa wineries. And Sarah McCrea at Stony Hill Vineyard and Tim Mondavi at Continuum Estate possess the kind of expertise and passion that would do their grandpappies proud.

These families have been true pioneers in America's most renowned wine region. Fred McCrea was the first and foremost champion of chardonnay in a region that had been focused almost exclusively on red grapes. Cesare and sons Peter and Robert (Tim's father) earned global renown at Charles Krug and Robert's eponymous winery.

"I am just trying to carry on the best that the family can offer," said Tim Mondavi during a recent Twin Cities visit.

Indeed, the Mondavis have offered up tasty fermented grape juice for more than a century — starting on the Iron Range. Cesare and Rosa Mondavi immigrated to Hibbing, where he became secretary of the Italian Club. "His fellow [immigrants] said 'We need wine,' so he was able to bring cold hard cash to California" to buy grapes and turn them into wine, said Tim.

When Prohibition hit, Cesare headed to California and Rosa stayed behind, thanks to a little known exemption in the Volstead Act (the National Prohibition Act)]: The head of a household could have 200 gallons of wine a year. So Rosa ran a boardinghouse with 18 rooms for young Italian miners. Voilà, 3,600 gallons of wine a year for the local denizens.

After a few years, the entire family embarked for central California, and when Prohibition ended, "Cesare said, 'Bobby, go to the Napa Valley. We are in it for the long term,' " said Tim, who like his father has visited Virginia, Minn., and Hibbing several times. "We could make fortified wine in the Central Valley, but we wanted to make great wine for our table."

In 1943, the family purchased the already-venerable Charles Krug. In 1966 Tim's dad founded Robert Mondavi, along the way serving as the prime worldwide ambassador for Napa wines, and in 2005 Robert and Tim started Continuum.

The grapes in the first few vintages came primarily from the valley-floor To-Kalon Vineyard that Robert (who died in 2008) had focused on for decades, but gradually Tim has been able to source entirely from his estate on Pritchard Hill. The wines are exceptional, pure, complex and intense but elegant. They sell for $250, but in my view are at least the equal of "cult" Napa reds that go for two to four times as much.

Goat farm beginnings

In the mountains on the opposite side of the Napa Valley, the McCrea clan has been toiling for 75 years, ever since Fred, a Red Wing native, purchased a goat farm in 1943. Stony Hill's hallmark wine since its 1952 inception has been a bracing, harmonious, cellar-worthy chardonnay that is about as close to a chablis as California gets, but their riesling is another perennially pristine beauty.

When Sarah McCrea, who turned 50 this month, got out of college, her grandfather had passed away and her grandmother was running the winery. "My parents hadn't gotten fully involved," she said, "and [my working there] didn't seem like anything in the realm of possibility. Everybody in the family has sort of taken their turn."

Indeed, her father, Peter, took over after his mother's death in 1991 and stayed the vinous course even as his neighbors were moving toward jammy, buttery chardonnays.

Sarah worked in marketing in Seattle for 10 years and in San Francisco for another decade, the inexorable lure of the family business beckoning. By 2010 her parents were pondering retirement, and she started working part time, "doing a little bit of everything."

"A lot of kids [of winery owners] get oenology degrees and were very directed," she said. "I got there late, but it was better than never and probably better, period. If I had started at 21, I probably would have left. I appreciate it more now and have more to contribute now."

That's especially important now that the winery has been sold to Long Meadow Ranch, a Napa operation famous for its farming practices. Stony Hill's output will grow a wee bit, but there's only so much vineyard land to be mined on a property in a remote site on Spring Mountain surrounded on three sides by state parks, "with a few goats on the fourth."

Her eventual job title likely will be vice president of marketing and strategy, playing into the skills she mastered at Starbucks and Jamba Juice. Now that nine months of heavy lifting are behind, as the sale unfolded, McCrea is excited to be working with a different kind of beverage.

"The quality of the wines, the personal connections, the family history," she said. "There is a big piece of myself wrapped up in all of this."

Amazing legacies have a way of doing that.

Bill Ward writes at decant-this.com. Follow him on Twitter: @billward4.