About 3,000 people gathered on Temple Square recently as part of a large-scale family reunion for the descendants of Henry Grow, a noted Salt Lake Valley architect in the mid-1800s.

Grow is best known for designing and constructing the roof of the Salt Lake City Tabernacle on Temple Square. Originally a bridge builder for the railroad in Pennsylvania, Grow used trusses to construct a roof without interior pillars, as Brigham Young had requested. Grow had five wives and left a large posterity.

Dean Grow and Marcia Nelsonhad been working on the Grow family genealogy together for six years and were talking about planning a reunion in 2017, the 200th anniversary of Henry Grow's birthday. They discussed the idea with Kimberly Herterich, another Henry Grow descendant, who contacted Elder Marlin K. Jensen, of the Seventy who also is serving as historian for The Church of Jesus Christ of Latter-day Saints, only to learn a reunion was already being planned for July 2012. Elder Jensen had already been working with Elder C. Scott Grow, also a member of the Seventy, and Robert Grow.

"We (Marcia, Kimberly and I) decided to get involved," Dean Grow said after relating the story. "We got Robert's phone number and decided we could all work together."

Members of the reunion committee used as variety of methods — including genealogy charts and information, obituaries, findagrave.com, death records, white pages and social media — to track down living descendants of Henry Grow. Nelson created a website to keep the records organized in a database and contacted people through ancestry.com. Dean Grow assisted Nelson in research, and Herterich manages a Facebook page for Henry Grow Jr.

"Marcia put in a Herculean effort; sometimes she said (she spent) 20 hours researching in a day," Dean Grow said.

When they began last winter, Nelson said she had entered 2,400 people in the database, including ancestors as well as descendants. Today, the database has more than 12,000 people listed.

"Those 10 months (of preparation) were surreal," Nelson said. "A lot of times I was up until 1 a.m. ...It was almost like a treasure hunt challenge."

Robert Grow, who served as committee chair for the 2012 reunion, said the Internet has been instrumental in helping the family reconnect.

"We couldn't have done this 20 years ago. There weren't all the databases," Robert Grow said in an interview prior to the reunion which was July 26-27. "The wonderful thing about communication is there will be sort of a virtual reunion going on that's bigger than this one."

Email: jhenrie@desnews.com