"It's an exciting moment," said Mahaiwe President Lola Jaffe. "This is a dream fulfilled.
Jaffe and her late husband, Edwin Jaffe, coordinated an extensive five-year restoration project for the theater that was completed in 2006.
The $9 million project revamped the facility both inside and outside. The theater now attracts about 50,000 people from around the area and brings in about $5 million to the local economy each year.
"We have restored the theater, and now it is a year-round endeavor," Jaffe said. "We now have events in October and November and we keep filling the seats. It's wonderful."
Since the register's creation in 1966, more than 2,400 landmarks have been designated across the United States. In addition to national recognition, entrance on the register means the theater will be eligible for federal historic preservation funds, when available, as well as federal tax benefits.
The theater's board of directors learned recently that state aid to the theater will be cut by about $150,000. The federal designation could help the Mahaiwe in its search for funding elsewhere.
Beryl Jolly, managing director of the facility, called the designation "one of the most significant events in the history of the theater."
Al Schwartz, longtime manager of the theater, said he was proud of that history.
"There are very few theaters still operating after 100 years," he said. "That in itself is a phenomenal record."
He said the designation honors "the most significant asset the theater has: The men and women who have worked here for 103 years, the people who, day and day out, have kept this theater going."
State Rep. William "Smitty" Pignatelli, D-Lenox, lauded the efforts of Lola Jaffe, adding that he was sure her late husband "was somewhere smiling down upon this."
Pignatelli added that a restored Mahaiwe was a huge asset to the downtown area.
"I think every downtown in Berkshire County would love to have a facility that attracts 400 to 500 people into the downtown area every night it's open," he said.
"It has been a great joy to be a part of this," said architect Michael Hardy. "When I go down Main Street and see the marquee lit up, that's all the thanks I need."
"When I started here in 1974, my dream was to see this theater restored," said Schwartz. Next week, he will be showing "The Wizard of Oz," one of the Mahaiwe traditions, for the 32nd consecutive year.
"May we be showing it for 132 consecutive years," he said.