The collection consists of a group of family papers and genealogical research pertaining to various Blair family members descended from Francis Preston Blair Sr. (1791-1876), the American newspaper editor, journalist, and politician. Family members represented include Francis Preston Blair Sr. (1791-1876); General Frank P. (Francis Preston) Blair Jr. (1821-1875), his wife Apolline Agatha Alexander Blair (1828-1908), and their children Francis Preston Blair III (1856-1914), Andrew A. Blair (1848-1932), and James L. Blair (1854-1904); Emily (Hockaday) Blair Henrotin (1883-1965), the daughter of Francis Preston Blair III; Gist Blair (1860-1940), the son of Montgomery Blair (1813-1883); along with others who are documented to a lesser extent, including Christine Biddle Blair Graham (1852-1915) and Violet Blair Janin (1848-1933). Materials include correspondence between family members and friends, personal and legal documents, military orders, photographs, printed materials and clippings, obituaries, family trees, genealogical charts and notes, and typewritten and published narratives detailing family history. Genealogical research files primarily pertain to the Blair family, but also include research on the Alexander, Cromwell, De la Porte, Hockaday, Madison, Price, Ceary (Cary), de Tuboeuf, Payson, Royall, Willis, Sterling, and Gist families.

Earlier materials in the collection shed light on the family's active role in 19th century American politics. Of note within the papers of General Frank P. Blair Jr. is a four-page letter, dated December 21, 1860, from Blair's father, Francis Preston Blair Sr., in which the elder Blair describes an exchange with United States Senator John J. Crittenden (1787-1863). Blair Sr. relates the advice he gave Crittenden regarding the Crittenden Compromise, the senator's ultimately unsuccessful proposal to resolve the secession crisis. In the same letter, Blair Sr. also discusses his attempts to find a position for his other son Montgomery Blair within the administration of Abraham Lincoln. Additionally, there is a small group of campaign materials from the 1968 Democratic presidential campaign of Horatio Seymour and General Frank P. Blair Jr.

The largest group of papers relate to Francis Preston Blair III. These mainly pertain to his time as a cadet at the United States Military Academy at West Point in the 1870s, and to a lesser extent, his first military assignment in the United States Army at Fort Hamilton, New York. Letters between Blair and his parents from his years at West Point reveal the high expectations the family set for their son. Supportive letters to Blair from notable figures such as General William Tecumseh Sherman, General Benjamin F. Butler, and General John Schofield show the reach of his family's connections.

Francis Preston Blair III was also in the same 1877 graduating class as Henry Ossian Flipper (1856-1940), the first African American man to graduate from West Point. One of General Frank P. Blair Jr.'s letters to his wife, Apolline Alexander Blair, mentions the admission of Henry O. Flipper and another African American cadet to West Point and indicates that Flipper passed the entrance exam with the highest score of any applicant. There are also newspaper clippings about Flipper filed with materials related to a centennial celebration for West Point's Class of 1877. Military orders from 1880 refer to an incident in which Johnson Chesnutt Whittaker (1858–1931), another African American cadet, was violently assaulted by his fellow cadets; Whittaker was ultimately expelled from West Point after being falsely accused and convicted of faking the incident.

Materials collected by Gist Blair (1860-1940) and others also document the family homes of the Blairs, including the Silver Spring estate in Montgomery County, Maryland, and the Blair House in Washington, D.C. Among other topics, Gist Blair's narratives include romanticized depictions of enslaved servants on his grandparents' estate. Another similar depiction of enslaved persons on a Virginia plantation can be found with genealogical research related to the Royall family.

While materials in this collection were accumulated and passed along by various Blair family members descended from Francis Preston Blair Sr., the primary family historians involved in assembling this group of materials were Emily Blair Henrotin, the daughter of Francis Preston Blair III and Florence Price Blair; and Henrotin's cousin Violet Blair Janin (1848-1933), the daughter of James L. Blair (1819-1852) and Mary Serena Eliza Jesup Blair (1825-1914). Janin appears to have passed her genealogical notes and collection of family papers onto Henrotin, whose annotations and explanatory notes can be found on a number of items. To a lesser extent, Gist Blair and Francis Preston Blair III were also involved in collecting genealogical materials related to the Blair family. One of the collectors, possibly Henrotin, was also invested in documenting African American history, as materials that relate to African Americans are often notated throughout the collection. There is also a file related to a 1916-1917 effort to create a memorial in Washington, D.C., honoring African American soldiers.