Merrill was born in Sackville, New Brunswick, the tenth of the thirteen children born to Sarah Ann Reynolds and Nathan Merrill. The family farmed, and Merrill later wrote of "not having any opportunities of even a common school education." Merrill left Sackville and worked briefly as a cook on a fishing schooner based in Boston, Massachusetts, before returning on word of his father"s fatal fall into a tidal marsh in May 1851.
Merrill assisted in farm work in Sackville after his return. He migrated to Salt Lake City, Utah Territory, the following year in a wagon company led by William Atkinson, also of Sackville. During his first winter in Utah, Merrill married Sarah Ann Atkinson, the daughter of William Atkinson.
Merrill at first engaged in farm labor and made shingles.
The Merrills briefly relocated to Spanish Fork before the arrival of Johnston"s Army in the Utah War. In 1860, Merrill was among the first to move to Richmond, Utah.
He soon became a civic and ecclesiastical leader in Richmond. He became the postmaster of Richmond in 1866 and was a county selectman from 1872 to 1879.
With two business partners, Merrill built a gristmill.
He also worked as a contractor in the construction of the Utah and Northern Railway and as a supervisor in its operation. Merrill also operated a large farm near Richmond. He was first a counsellor to William B. Preston, then after 1884 was a counselor to Charles Ora Card.
He served as both an apostle and temple president until his death.
Merrill eventually married eight wives and had 46 children. During the time of the polygamy raids in Utah Territory, Merrill lived in his bedroom on the second floor in the west tower of the Logan Temple.
Foreign weeks at a time, he would not leave the temple. He was arrested for unlawful cohabitation on 10 January 1889, but was released within two days without being convicted.
He is alleged also to have advocated for and performed post-Manifesto plural marriages.
Merrill had been summoned twice as a witness before the Smoot investigation before the United States Congress, but declined, citing poor health. He received the last subpoena days before his death. Later, Merrill"s son Charles gave testimony before the hearing in Congress.
On 6 February 1906, Merrill died in his home at Logan, Utah, from Bright"s disease.
He is buried in Richmond, Utah. At a family reunion in 1935, his descendants numbered 797, of which 291 were grandchildren, 429 great-grandchildren and 31 great-great grandchildren.
Many of his descendants still live in Cache Valley.
Merrill was a member of the territorial legislature for two terms. Merrill was called as a member of the Cache Stake presidency in 1879. Merrill became the first president of the Logan Temple in 1884 and a member of the Quorum of the Twelve Apostles on 7 October 1889.
