Cox was born in December 1832 in Powhatan County, whether free or enslaved is not certain. The maiden name and surname of his mother, an African American woman named Louisa, are not known, nor is the name of his father. It is likely that Cox was closely related to, a Powhatan County native a few years younger than he who served in the Convention of 1867–1868. Details about Cox’s life are scarce, and researchers have occasionally confused him with Henry Coy, a freeborn black carpenter in the county who was approximately six years older. When Cox married Rachel E. Harris on November 23, 1867, he identified himself as a thirty-five-year-old widower and shoemaker. They had two daughters, and the 1870 census (which listed him as a farmer able to read and write) indicates that in that year he also had a sixteen-year-old son. In 1871 Cox purchased a thirty-seven-acre farm worth $666.
Described later as a plain man well-liked by his fellow citizens, Cox became interested induring Reconstruction and beginning in 1870 served concurrent two-year terms as a Powhatan County justice of the peace and constable. In July 1869, in the first election in which African Americans voted for members of the General Assembly, he won one of three seats representing Chesterfield and Powhatan counties in the House of Delegates. A conservative newspaper characterized all three delegates, two of whom were African Americans, as “Ultra Radicals.” Following a redistricting of the assembly, Cox won reelection to two-year terms in 1871, 1873, and 1875 as the sole delegate from Powhatan County. He did not seek a fifth term in 1877.
In his first term Cox was appointed to the lowest-ranking seat on the Committee on Labor and the Poor and was also the lowest-ranking member of the Committee on Militia and Police. He retained his assignment on the latter during his second and third terms, and during his third and fourth he also held a low-ranking seat on the Committee on Officers and Offices at the Capitol. None of the appointments was to an influential committee, and there is no evidence that Cox introduced any significant bills during his eight years in the House of Delegates. The assembly’s records and newspaper accounts of its sessions do not indicate whether he spoke during debates. Characterizing his service is difficult because he was sometimes absent or did not vote when present, but at election times newspaper reports usually identified him as aor a Radical.
In April 1870 Cox attended a Richmond convention of African American workingmen that adopted resolutions calling for organizing laborers, accused the state’sof attempting to reduce the number of Republican voters, and advised “colored men to be honest, sober, and industrious.” Later that month Cox also attended the state convention of the Republican Party, which called for enforcement of the and amendments to the Constitution, advocated public education at public expense, and endorsed the new state constitution. On January 10, 1872, he and several other African American members of the assembly joined legislators from other states in Washington, D.C., to discuss federal civil rights legislation with the president. Two days later Cox was back at work in Richmond, where he voted with the majority of House members in favor of reducing the per diem and mileage allowance for members of the General Assembly. He was a member of the Resolutions Committee at an 1875 state convention of approximately one hundred African American delegates who met in Richmond to address a lack of jobs and who organized a short-lived Laboring Men’s Mechanics’ Union Association.
Cox and his wife moved to Washington, D.C., about 1881. Seven years later his property in Powhatan County was sold, possibly for nonpayment of taxes. Cox last appears in public records in 1910, when the Washington city directory listed him as a shoemaker residing at 202 Massachusetts Avenue, N.W., where he had lived for a decade or more. His name does not appear in the census taken in April of that year. The date, place, and circumstances of Henry Cox’s death are not known, nor is his place of burial.