Griffith E. Thomas (1814-1899) was "one of Loudoun's oldest and most highly respected citizens" when he died. Buried in the Mount Zion Cemetery, he left behind a wife, Rebecca Wright Thomas (1821-1911), and seven children. Beginning in 1934, his descendants established an annual family reunion held at the Mount Zion Baptist Church. Except for the year 1935 when the meeting was canceled due to an outbreak of infantile paralysis, the family members have reunited once every year. At each meeting, family records births, deaths, and marriages that occurred in the last year, gives each graduating high school and college student a gift of money, and gives a gift of honor to the matriarch. Meetings are presided over by the elected president, vice-president, secretary, and treasurer. Over the years, attendance has averaged 91 family members. The family still meets annually.

The Mount Zion Baptist Church was founded in 1851, and in 1864, it was the site of a Civil War skirmish between Mosby's Rangers and the Second Massachusetts Cavalry. For many years, the Thomas family gave money to Mount Zion as thanks for allowing a picnic to be hosted on its grounds, as well as contributing money to the upkeep of the graveyard, where many Thomases were buried. In 1985, after expressing concern about the maintenance of the grounds and cemetery, the family formed the Mount Zion Cemetery Company to assist in its preservation. Along with trustees of the Mount Zion Church, the Griffith Thomas family funded the placement of a historical marker in 1986.