For Ruben Sanca, the Shamrock Shuffle was on the road to the 2012 London Olympics. Sanca won last year's Shamrock race in downtown Manchester, an Irish-themed 2-miler preceding the St. Patrick's Parade, and later competed in a 5,000-meter qualifying heat at London.

Other participants are thrilled to simply reach the giant clover painted on Elm Street and cross the finish line. Last year's Shamrock Shuffle drew more than 2,500 runners and walkers, including women's champion Kara Haas of Chelmsford, Mass., clocked at 10 minutes, 55.76 seconds. Sanca, of Dracut, Mass., represented Cape Verde at London last summer. In March, he crushed the Shamrock field by running a 9:05.77.

Another sold-out Shamrock Shuffle, headquartered at Veteran's Park, is set for Sunday. The Kids Leprechaun Run begins at 10:45 a.m., followed by the Shuffle at 11:15 a.m. Proceeds will benefit New Horizons for New Hampshire. The St. Patrick's Day Parade begins at noon.

For those preparing for the Boston Marathon, there's a much longer race on the Seacoast on Sunday. The 18th Annual Eastern States 20-Mile Race, formerly known as the Border to Border, takes runners through six towns and two states. The 20-miler begins at Portmouth High School at 11 a.m. and finishes across the Massachusetts border in Salibury. Casey Moulton, a Pelham High graduate, won last year's event at 1:45:40. Twin brother Patrick finished third.

The 14th annual Run for the Border Half Marathon, which begins at Wallis Sands Beach in Rye, also begins at 11 a.m. on Sunday. Casey Carroll of Dover is the defending champion in the Run for the Border Half Marathon. Carroll ran a blistering 5:51 pace and finished at 1:16:34 last year.