Now in its fourth year, the Napa-to-Sonoma Wine Country Half Marathon will bring a record number of participants and a top field of elite runners to Napa and Sonoma on Sunday. This increasingly popular race now attracts a sold-out field of 2,400 runners and wine enthusiasts.

The 13.1-mile half-marathon race begins at 7:15 a.m. at Cuvaison Carneros Estate winery, 1221 Duhig Road, winding its way from southern Napa County into Sonoma through the Carneros wine region. Runners will pass Gundlach Bundschu Winery and then turn off Denmark Street onto Seventh Street East, and will go left on Lovall Valley Road onto the bike path. Because of a decision by the Sonoma City Council, the race will not be ending in the Sonoma Plaza this year, but will now detour to First Street East and finish next to Depot Park.

It’s a USA Track & Field-certified course.

One third of the participants are from out of state, and the event is expected to generate over $1 million from tourism and services this year. Even after selling out in early May, the race has seen continued interest from runners across the country.

“We’ve received dozens of e-mails from people who booked their flights and hotels first and then found out the race was sold out,” said event director Matt Dockstader of Destination Races.

In the new issue of Runner’s World Magazine, the Napa-Sonoma Wine Country Half was just picked as the best race finish for half marathons in the country. The race is recognized for its scenic course, wine awards and hospitality, highlighted by a post-race wine and music festival.

Look for a fast group of runners to be leading the pack this year. Back to defend their respective titles are Celedonia Rodriquez, a Santa Rosa native who now lives and trains in Alamosa, Colo. Rodriquez finished last year’s race in a course record time of 1 hour, 6 minutes and 34 seconds. Celedonia’s main competition is expected to come from Fernando Cabado, the American record holder in the 25K, and John Weru, a recent winner of the San Francisco and Lake Tahoe marathons.

The women’s elite field is especially strong this year. Elizabeth Daane, from Ireland and now living in Reno, returns to defend last year’s title. Mary Coordt, the 2004 winner from Sacramento, will also be returning to Napa/Sonoma. Coordt has won the Napa Valley and Big Sur Marathons, and competed in the 2000 and 2004 USA Olympic Marathon trials. She will also be giving a nutritional seminar at the race expo in Sonoma from noon to 1 p.m. on July 14.

Also competing is the first American female finisher in this year’s Bay-to-Breakers, Magdelena Lewy-Boulet, and a 2008 U.S. Olympic marathon trials qualifier and four-time All-American at the University of Colorado, Patty Rogers.

A post-race festival is open to the public but the wine tasting is limited to race participants and their guests. In addition to receiving a colorful finisher’s medal and shirt, each runner also receives a logo wine glass, good for tasting in the park of different varietals from wineries of the Sonoma and Napa Valleys. Nearly 4,000 people are expected to attend this year’s festival.

A race expo is open to the public and will be held at the Sonoma Valley Inn on July 14, from 10 a.m. to 5 p.m.

Over 150 volunteers are needed to help stage this year’s event. Many of them come from Hanna Boys Center, the primary event beneficiary. Proceeds also benefit the athletic programs for local middle schools and essential services for the non-profit organization Vineyard Worker Services, recently added to provide more volunteer support.

Those interested in joining the volunteer team can e-mail raceinfo@destinationraces.com.

For more event information, visit www.runcarneros.com.