It looks like by 1860, both Nancy and Rebecca were both widows.
1860 Census-Hopkins Co.:
Rebecca D., 40, f, farmer, AR
James, 19, m, laborer on farm, TX
Mary, 18, f, serving, TX
David, 16, m, laborer, TX
Margaret, 14, f, TX
William, 12, m, TX
Nancy, 24, f, seamstress, TX
Rebecca, 4, f, TX
William, 2, m, TX
J.G, 21, m, TX
Harriet A., 18, f, IL
David, 42, m, farmer, AR
Annie, 35, f, TN
Mary, 3, f, TX
William, 1, m, TX
Frank, 13, m, TX
James, 12, m, TX
Edward, 10, m, TX
Casandre, 7, f, TX
T.C., 38, m, farmer, AR
Elizabeth, 36, f, IN
Mary, 15, f, serving, TX
James, 13, m, TX
John, 12, m, TX
Albert, 10, m, TX
William, 8, m, TX
Nancy, 6, f, TX
Isabella, 2, f, TX
John L., 20, m, w, farmer, TX
Susan, 20, f, w, keeping house, MO
Edward, 1, m, w, TX
Clara, 9, f, w, TX
Isabella, 10, f, w, TX
Nancy, 15, f, w, TX
(The last three are apparently sisters to John L.)
James, 22, m, w, farmer, TX
Malinda, 22, f, w, keeping house, MO
Lu Ella, 2, f, w, TX
Joseph, 1, m, w, TX
(Brothers, John L. and James Clark may have married sisters, Susan F.C. and Malinda M. Bartlett)
Perry, 48, m, w, farmer, IN
Casander, 38, f, w, keeping house, AR
John, 13, m, w, TX
Charles, 9, m, w, TX
Casander, 15, f, w, at home, TX
I believe there were two other brothers to David and Thomas Carr, both from AR - Benjamin and William Clark.
E.H., w, m, 30, wagon maker, TX, TN, IN
Sarah, w, f, 24, wife, house keeper, TX, AL, KY
J.E., w, m, 4, son, TX
Ada, w, f, 3, dau, TX
Living two houses over with the Mary J. Lollar family is:
Clark, James, w, m, 32, blacksmith, TX, TN, IN
(Don't know what happened to the rest of his family.)
I did not find any of your Clarks in the 1900 Census, nor 1910 Census Index.....did they move out of the county by then?
Hopkins Co. Marriages, 1846-1890:
Edward H. to Merrell, Sarah D. on Oct 28, 1875, Vol. 4, Pg. 155
Frank H. to Yates, Mary A. on Apr 2, 1866, Vol. 2, Pg. 342
J.E. to McKinney, M.E. on Oct 12, 1884, Vol. 5, Pg. 328
James P. to Bartlett, M.M. on Aug 25, 1866, Vol. 2, Pg. 375
John L. to Bartlett, Susan F.C. on Oct 26, 1867, Vol. 3, Pg. 131, (Issued-NR)
Excerpt taken from the book by Florene Adams, Hopkins County and Our Heritage:
On the history of Hopkins County, talking about the Tarrant community, which is where the first county seat of Hopkins Co. was established....
The first wedding on the 16th day of October, 1843. T.C. Clark and Elizabeth B. Hargrave; the license was procured at Clarksville and Esq. Abner McKinzie, of Clarksville, performs the ceremony.
From the book, Pioneers of Hopkins County, Texas, Vol. II:
There is mention of a Cassandra Clark marring James Perry Hargrave on Sept. 28, 1848. It listed her father as Gilbert Clark of Kentucky. She was born Feb. 9, 1831. Her parents had lived in the Red River District of Texas since 1834. James Perry and Cassandra Hargrave lived in the Sulphur Bluff community of Hopkins County.
The reason I mention this is because in another story, there is mention of a Rebecca Clark marrying William Gregg on Dec. 28, 1834. He was born Oct. 26, 1806, north of Troy, IL, died May, 1848, near Clarksville, Texas. Rebecca Clark was born in 1819, in North Carolina. She was the daughter of Gilbert Clark, who moved to Texas when Rebecca was 14 years old. It goes on to list the children of William and Rebecca Gregg. This story was submitted by Iva Elizabeth Mitchell. The story about Cassandra was submitted by Cynthia Hargrave Orth, written by Eli Hargrave. There are many, many Hargrave in Hopkins County. They were a founding family. There are many Hargrave books in our Research Library in Sulphur Springs.
This is taken from the book, Roots and Branches, Vol. II:
John Clark, d. 1792
Benjamin Clark, b. Jan., 1759, in Dobbs, N.C.; m. Mary McLendon (dau. of Jesse McLendon and Elizabeth Ball); d. Feb., 1838
Gilbert Clark, b. Jan. 12, 1791, in Edgefield Co., N.C.; m. Mary Ann Ward (b. Sept. 11, 1796 in Duplin Co., N.C.; d. Feb. 4, 1852; dau. of Luke Ward and Rebecca Drew) on Oct. 11, 1811; d. Sept. 16, 1854 in Hopkins Co., TX
Cassandra Clark, b. Feb. 9, 1831, in Miller Co., AR; m. James Perry Hargrave on Sept. 28, 1848; d. Dec. 29, 1912 in Hopkins County, TX.
This was submitted by Mrs. Thera Bagley, 8322 Huckleberry, Anchorage, AK, 99502. (Thera was a great, great granddaughter to James Perry and Cassandra Clark.)
From the book, Hopkins County Remembered:
There is another story about the marriage of Thomas C. Clark and Elizabeth Hargrave being the first in the county. There was no minister in the county, so Abner McKenzie, the Justice of the Peace at Clarksville, rode over on horseback to perform the ceremony.
Also, from this book:
Gilbert Clark, a Presbyterian preacher, native of Kentucky, came here from Red River County during 1843, and his son, Thomas Clark, married a daughter, Barilla (?), of William Hargrave, Oct. 16, 1843, this being the first wedding in the neighborhood. Perry Hargrave, brother of the bride-to-be, went with Clark on horseback to Paris for the license and they had to swim Sulphur River on the way. Abner McKenzie, J.P. at Clarksville, came on horseback to perform the marriage ceremony.
Hope this information helps you with your family research. Good luck.