In the 1820s and 1830s a great wave of Southerners moved to Indiana. Perhaps the most famous of these were Abraham Lincoln and his family. One young couple, John Jeter and Elizabeth Coleman Crosby, joined this migration. Their family later became influential in the early history of the church.
John was from an old South Carolina family and Elizabeth was from an old Virginia family. Their parents and grandparents served in the Revolutionary War. Elizabeth’s parents moved from Virginia and settled in Union, South Carolina.  Elizabeth married John Jeter Crosby and they went to settle in Indiana.
The Crosbys had six children: William, Ann, Susan, Syntha, Elizabeth, and Nancy.
The family histories note that they had a hard time adjusting to life without slaves, so John and Elizabeth and other members of the Crosby family moved south to former Choctaw lands in Monroe County, Mississippi.
Several years later the Choctaw tribe left Mississippi in a forced march to Indian Territory (now Oklahoma) that one of their chiefs called a “trail of tears and death.” The year after the tribe left, one of the Crosby daughters, Ann, married Daniel Monroe Thomas, the son of Henry and Esther Thomas. 
Many members of the Crosby and Thomas families joined the Church of Jesus Christ of Latter-day Saints and belonged to the Tombigbee Branch in Mississippi.  They were converted through the efforts of John Brown, who then married Ann’s sister Elizabeth. Daniel Thomas was also instrumental in introducing the Book of Mormon to a large number of family members and others who joined the Church.
Ann Crosby Thomas may have been baptized as late as 1843, but she may have been baptized before then. The records are unclear.
Daniel accompanied John Brown to Pueblo, Colorado, and then went back to help move his extended family West. Did Ann go with him to Colorado or did she remain with other family members while he traveled?
Daniel’s unmarried brother Elijah joined the Mormon Battalion and was among those who discovered gold at Sutter’s Mill.
When Ann’s father, John Jeter Crosby, died in 1840, his slaves were divided between his wife and children. Daniel and Ann took two of the slaves to Utah, Philemon and Tennessee. A Crosby descendant notes that Philemon was one of four men she blithely called “bucks,” or breeding slaves, along with Osea [Hosea?], Hardy, and Hark.
Members of the Crosby family sent two slaves in the first 1847 pioneer company with Brigham Young: William and Syntha Crosby Lay sent Hark, and William Crosby sent Oscar.  In addition, their close friend James Flake sent Green, who reportedly drove Brigham Young’s carriage into the Salt Lake Valley. These three slaves were in charge of preparing accommodations for their owners who would arrive later.
Daniel and Ann met members of his Thomas family part way across the plains and helped them to the Salt Lake Valley. They arrived in October 1847 in the Edward Hunter/Jacob Foutz Wagon Company.
When they arrived in the Salt Lake Valley, many of the Mississippi Saints moved into the South Cottonwood area of the Salt Lake Valley. Ann’s mother died there in 1849.
Daniel and Ann and other family members moved further south and showed up in Utah County in the first territorial census.  The census shows Daniel and Ann living in a household with four children: Daniel, age 4, Henry and Ann, twins, age 3, and John, age 2. The first three were born in Mississippi and John was born in Deseret (Utah). Based on naming conventions (first son named after father, second son named after grandfather, daughter named after mother, third son named after other grandfather) and the fact that twins ran in their family, they should be Daniel and Ann’s children. I have tried to figure out if they could have belonged to a relative since they don’t show up in any of the Mormon Pioneer Overland Travel records, but no other related family matches the criteria to have been their parents. These four children must have all died at an early age, because they do not show up in the next census and cannot be located in any census or vital records. Curiously enough, Daniel’s biography notes that he didn’t have any children.
When a large number of pioneers went to settle San Bernardino, California, a good part of the settlement was made up of Mississippi and other Southern Saints. Daniel and Ann were among them. They took one slave, Toby. Although I have looked long and hard and traced many of the other early Utah slaves, I have not been able to find out what happened to any of the Thomas slaves, Philemon, Tennessee, or Toby. 
When they crossed the border into California, the slaves they took with them were freed since California was a free state. Most of these former slaves remained in San Bernardino or Los Angeles. 
Leonard Arrington tells a little story about life in San Bernardino:
Possessed of a sparkling sense of fun, [the Southerners] preserved a delightful incident in their records of an early school in San Bernardino that pinpoints one of the differences between the Southern pupils and their Yankee schoolteacher. A first-grader asked the teacher how to spell “rat.” Somewhat impatiently the teacher spelled it for him, “R-A-T.” Fixing her with a look of scorn he replied: “I don’t mean mousey rat. Anybody knows how to spell dat. What I mean is like in ‘Do it rat now.’”
Daniel served as County Judge and Postmaster in San Bernardino. He was known as a beautiful singer and a schoolmaster of good reputation.
When the San Bernardino settlement was called back to Utah, Daniel and Ann Thomas went to live in Beaver, Utah, with other members of the San Bernardino community. Daniel again served as Judge and Postmaster. The census there shows a 14-year-old girl named Mary Thomas living with them, born in Mississippi, but once again her identity is a puzzle. If she was a daughter, she should have shown up in the previous census. She never shows up again.
At some point, Daniel and Ann took a young Scottish orphan, Ninian Miller, into their home. Ninian’s father had died on the way to Utah, and his mother had died shortly after arriving in Utah. Ninian lived in the Thomas home until he married Sarah Kartchner in 1877 and went to settle the Little Colorado Region of Arizona.
After living in Beaver for several years, Daniel and Ann moved south to Utah’s Dixie region. Some of the San Bernardino settlers had joined earlier Indian Mission settlers in this red rock area of southwest Utah, and then the area was settled by hundreds of other families called by Brigham Young to the Cotton Mission. Daniel and Ann Thomas and Ninian settled first in an area now in Nevada. At the time it was called Overton, Rio Virgin County, Utah Territory. Some of the other members of their family settled in the area including Daniel’s brother Elijah and his family, Ann’s brother William Crosby and his family, and her sister Syntha Crosby Lay and her family. All of Ann’s extended family had come to Utah except for her sister Susan Crosby Watts Harris. Near the end of her life, twice widowed, blind, all her children dead, Susan was left in the South without means of support, so her nephew John Brown traveled to her home to take her to Utah where she spent her last years among family.
In 1877, Daniel and Ann Thomas went to do their temple work in the brand new St. George Temple. The temple president, Wilford Woodruff, had had many amazing adventures during his mission in the Southern States, and surely they shared memories of the old times. Daniel and Ann participated with Wilford Woodruff in the Eminent Men and Women project, Daniel doing the work for David Farragut (an admiral for the Union during the Civil War, best known for his line, “damn the torpedoes…”), Ann doing the work for Mary O’Connell, the wife of the Great Liberator and abolitionist Daniel O’Connell.
Ann died less than a year after doing this temple work. She was buried in the St. George Cemetery. Three years later, her husband married Mary Ann Chandler. Daniel’s death is recorded as being in St. George in 1894, but no record exists of his burial, or of the death or burial of his second wife.
 Was Fort Union in Salt Lake Valley named after Elizabeth Coleman Crosby’s old home?
 Some of the dates, places and movements are hard to pin down and are contradicted in the different records. I have pieced their lives together as best as I could.
 There were two Crosby families in the early church, the Mississippi Crosbys, and Jesse Wentworth Crosby and his family from Nova Scotia, Canada. The two families were not related. There was also a different Daniel Thomas who joined the church in Kentucky and crossed the plains. This other Daniel Thomas also had a brother named Henry and a father named Henry who joined the church.
 Although he spent much of his life among members of the church, Ann’s brother-in-law William Lay never joined the church.
 The extended Crosby family (mother Elizabeth Coleman Crosby, John and Elizabeth Crosby Brown, William and Syntha Crosby Lay, Daniel and Ann Crosby Thomas, John and Nancy Crosby Bankhead, and John’s brother George Bankhead) owned about two-thirds of the slaves listed in the 1850 (1851) Utah Territorial Census. Other early slaveholders were James and Agnes Flake, Abraham O. Smoot, William Mathews, Robert and Rebecca Smith, Williams Washington Camp, Charles C. Rich, Monroe Perkins, and Reuben and Elizabeth Perkins. (Have I missed anyone? Some of the records disagree on numbers and names. See also footnote 6.)
 Here is a list of the documented black slaves in Utah in the 1840s and 1850s. I may have missed some, and several may be listed in more than one family, including those who are listed as unnamed. [Updated March 7, 2012.]
Bankhead (John and George): Sam, Nancy, Alexander, Thomas, Nathan, Susan, Miriam, Sam, Rolly, Howard, Dan, George, George Nathan, Rose, Ike Valentine, John Priestly, Dan Freeman, Lewis, unnamed man who died on the way to Utah.
Brown (John): Betsy or Betty (Crosby Brown Flewellen), Henry who died on the way to Utah.
Camp (Williams): Charlotte, Dan, Ike, Ben. Perhaps also Thomas Coleman.
Crosby (Elizabeth): Edy, Mary, one other unnamed.
Crosby (William): Vilate (mother of Hark Lay, Oscar, and Martha Crosby Flake), Toby, Grief Embers, Oscar, Nelson, Mary, Henderson, Rose, Nancy, Samuel, George, Martha (Crosby Flake).
Dennis (William): Nancy or Mammy, Jim Valentine and his wife, Jim.
Drummond (Judge William): Cato.
Ewell (Mary Bland): Chloe.
Flake (James and Agnes): Green, Elizabeth “Liz,” Martha.
Forbush (Hyrum): John Priestly Bankhead.
Hooper (William): Shep.
Johnson (Joel H.): Tom Coulbourn.
Kimball (Heber C.): Martha (Flake).
Lay (William): Hark, Thompson, Harriett, Knelt, Lucy, (Henderson, also listed in Crosby family).
Lewis (Mrs. David): Jerry.
Mathews (William): Uncle Phil.
McKown (Frances): two unnamed.
Perkins (Jasper): Mary.
Perkins (Franklin Monroe): Ben (sold to Mr Sprouse).
Perkins (Reuben): Frank or Franklin, Esther, Ben, Sarah, Mary Ann, Downey, Ephraim, Wesley, Albert, Manissa or Manassah, Thomas, Charlotte, James.
Pinney (Dr.): Marinda Redd Bankhead.
Redd (John Hardison): Marinda (Redd Bankhead), Chaney or Chancey, Anna or Amy, Venus (Cupid), Luke, Sam, possibly one or more other unnamed slaves.
Rich (Charles C.): Dick, five other unnamed slaves.
Robinson (Joseph): John Burton.
Smith (Robert): “Aunt,” Hannah (Sunily), Biddy, Ellen, Ann, Harriet, Ann, Lawrence, Nelson, Jane, Charley.
Smith (William): three unnamed.
Smoot (Abraham O.): Jerry, Alex Bankhead, probably others.
Sprouse (Silas or Sylas): Daniel, Ben (from Monroe Perkins).
Thomas (Daniel Monroe): Philemon, Tennessee, Toby.
Williams (Thomas S.): two female slaves.
There were some pretty dodgy practices and events related to slaves and slave-holding in Utah Territory, but besides the dubious ethics of owning humans as property, I have never read anything of that sort about the extended Crosby family. They seem to have been model citizens, very public minded, and by all reports treated their slaves well.
 The Bankhead and Perkins and a few other slaves stayed in the Salt Lake Valley and were freed upon emancipation. Several others were freed before then,
including Green Flake, who was deeded to the Church as tithing by Agnes Flake after her husband died. He was freed and remained in Utah. [ATT.—The story about the human tithing may have been told by descendants without any particular knowledge of the circumstances, and it seems to be contradicted by a number of contemporary sources. See comments.]