Mary [later changed to Merry] Elizabeth Dalton was born November 6, 1925, in Sault Ste. Marie, Ontario, Canada, to Spencer and Dorothy Boehmer Dalton. She attended a Baptist church in Galt, Ontario, heard Bible stories from her grandmother, and was converted at the age of nine. She graduated from high school in 1944 and then attended Kitchener-Waterloo Nurses' Training Hospital until 1948. Merry attended Wheaton College for one year beginning in the summer of 1948, but did not finish her degree. It was at Wheaton that she met Paul Long and they were married in June 1949. In 1950, the Longs had their first child.

After Paul attended seminary, the Longs went as missionaries under the Southern Presbyterian Mission Board to Bibanga, Bakwanga, in the Belgian Congo (now Zaire), where Merry worked as a nurse in the hospital and Paul became the director of regional schools and engaged in evangelistic work. In addition to the work in the primitive hospital, Merry made time to teach her children as well as to teach medical subjects in the Chiluba language at the hospital. During the 1960-61 Rebellion in the Congo, the Longs were forced to leave.

In 1963, the Longs were assigned to do pioneer church planting work along an eight hundred mile stretch of the Brasilia-Belem highway in North Goias, Brazil. After eleven years in that area, Paul was assigned to an area on the Trans-Amazon Highway. While in Brazil, Merry started public health clinics, with help from a German baroness, taught Sunday school, and worked in the nursery of the Brazilian churches the Longs attended, as well as cared for her own children.

After the children were grown and Paul received his Ph D degree at Fuller Theological Seminary and began teaching in Jackson, MS, Merry returned to college to complete her BA degree at Mississippi College. The Longs had five children, all of whom graduated from Wheaton College: Paul Brown II (BA '72), Mary Elizabeth (BA '74), Virginia Ann (BA '76), Stephen Dalton (BA '79), and Charles Alexander (BA'82).

Merry Dalton passed away on March 15, 2010.