Thomas D. Merrick was born on 23 May, 1814, in Hampden County, Massachusetts. He later moved to Indianapolis IN and Louisville KY before ending up in Little Rock.
On January 17, 1841, he married Anna M. Adams of Kentucky at Christ Episcopal Church in Little Rock. They had seven children: George, Annie, Ellie, Mollie, Lillian, Dwight, and Thomas. Thomas died at age ten.
Merrick became a prominent member of the Little Rock business community, as a merchant and cotton broker. He was involved in Freemasonry, holding the position of Grand Secretary of the Grand Lodge of Arkansas in 1845.
In 1855 Merrick entered into a business partnership with future LR Mayor John Wassell. Merrick was also involved in city politics, serving on the city council and also as mayor from January 1854 to January 1855.
He saw active service during the Civil War. On February 6, 1861, Merrick delivered an ultimatum to Captain James Totten of the United States Arsenal at Little Rock, demanding the surrender of the federal troops. Merrick also raised a regiment of Confederate Arkansas Militia, holding the rank of Colonel of Infantry at Camp Conway, near Springfield, Arkansas. Following the Battle of Shiloh (April 1862), Merrick resigned his commission and returned to Little Rock.
Merrick died in his home in Little Rock on March 18, 1866. He is buried in Mt. Holly Cemetery.