Fans of 100-mile trail races are in luck this weekend. A trio of triple-digit distance events is on tap: the Hardrock 100, Vermont 100, and Tahoe Rim Trail 100.

Massachusetts ultrarunners will be competing in all three.

The hardest of the three events – Hardrock – is considered to be the toughest 100-miler in the United States. It features two loops of a course high in the mountains around Silverton, Colo., and includes approximately 34,000 feet of vertical gain. Runners have 48 hours to complete the course and “kiss the rock” at the finish line.

The race begins at 6 a.m. MST (8 a.m. EST) Friday, and the finish line closes at 6 a.m. Sunday.

Two-time champion and course record-holder Kilian Jornet will be back to pursue another victory, and he will be joined by two Bay Staters who also have completed the course before. Five-time Hardrock finisher Jeff List of East Falmouth, Mass., is back. List, 57, finished Hardrock in 2009 and 2011, as well as each of the past three years. List finished 80^th overall in 2015, reaching the finish line in 42:35:49. He will be joined by Christopher Agbay, 39, of Jefferson, Mass., who earned his first Hardrock finish in 2015 when he placed 64^th overall in 39:46:52.

Out West in Carson City, Nev., the Tahoe Rim Trail 100 begins at 5 a.m. PSD (8 a.m. EST) Saturday, and runners will have 35 hours to navigate the course and its approximately 20,000 feet of vertical gain. Bill Howard of Winchester, Mass., will represent the Bay State at the starting line. The 67-year-old Howard will attempt to add Tahoe to a list of 100-mile finishes that includes the 2015 Javelina Jundred in Arizona, the 2014 Run Rabbit Run in Colorado, the 2013 Vermont 100, and the 2011 Lean Horse 100 in South Dakota.

Meanwhile, a few hours north in West Windsor, Vt., the 28^th annual Vermont 100 Endurance Run will begin at 4 a.m. Saturday. The event harkens back to the earliest days of the sport by including a 100-mile horse race. The race course takes place mostly on dirt and gravel country roads and includes more than 14,000 feet of vertical gain. Runners have 30 hours to complete the course.

More than 300 runners are expected to toe the starting line, and nearly 50 of the entrants hail from Massachusetts. Included among the Bay Staters is 37-year-old Brian Rusiecki of South Deerfield, Mass. Rusiecki is a two-time Vermont 100 champion (2012, 2014) and the 2015 runner-up, and he will be pursuing his eighth consecutive finish. He set the course record of 14:47:35 during the 2014 race.

Other notable names include 39-year-old Eric Ahern of Somerville, Mass., and 34-year-old Jake Dissinger of Leeds, Mass. Ahern has recorded four straight top-10 finishes at the Vermont 50 and finished eighth overall at The Canyons 100K in Foresthill, Calif., in early May. Dissinger won the Manchester 2 Monadnock 55-miler in May, and he was the runner-up at the 2015 Ghost Train 100-miler.