The 22d annual Groton Road Race will be held Sunday beginning and ending at Groton-Dunstable Regional Middle School. The race is the first in the Nashoba Valley Grand Prix series, which will continue with events in Harvard, Littleton, and Ayer later in the year. The Groton race features Tots’ Trot, 2K Fun Run, 5K, and 10K events, with the youngest participants setting off at 10:45 a.m., and the longer competitions having staggered starting times; as the last event, the 10K begins at 1 p.m. Race-day registration begins at 9 a.m.; for more information, visit www.grotonroadrace.com.