The number of people who finished a triathlon in the United States last year reached an estimated 2.3 million, which represents a 55 percent increase over 2009, according the Sporting Goods Manufacturers Association.

In addition, USA Triathlon, the sport’s primary governing body in the United States, reports that its membership reached an all-time high of more than 140,000, not counting about 326,000 one-day registrations.

Both numbers demonstrate the sustained growth that triathlon is enjoying in the country. The number of athletes signed up for the Hy-Vee 5150 U.S. Championship and Hy-Vee Triathlon bears that out.

The number of Hy-Vee participants stood at 1,841 last week; about 400 ahead of last year’s pace.

At last weekend’s Nautica New York City Triathlon, the final qualifier for the Sept. 4 Hy-Vee 5150 championships, organizers said registration filled up within six minutes after it opened. Entrants came from 43 states and 26 countries. Record participation has been reported this year at events across the country, from kid’s triathlons to Ironman endurance races.

“This data supports what we are fortunate enough to observe on a daily basis at USA Triathlon — more and more people are flocking to our sport annually because of the incredibly healthy lifestyle it promotes and the exciting and rewarding challenge it presents,” USA Triathlon CEO Rob Urbach said on the organization’s website. “We are thrilled to be a part of the consistent and dramatic growth of multisport on a national and worldwide level and we look forward to continuing to help take our sport to new heights in the future.”

In addition to record membership, USA Triathlon also reached all-time highs in the number of sanctioned events, coaches, race directors and clubs.