Background: Benjamin Solomon Carson Sr. (born September 18, 1951) is an American neurosurgeon, author and politician serving as the 17th and current United States Secretary of Housing and Urban Development since 2017, under the Trump Administration. Prior to his cabinet position, he was a candidate for President of the United States in the Republican primaries in 2016. Born in Detroit, Michigan, and a graduate of Yale University and the University of Michigan Medical School, Carson has authored numerous books on his medical career and political stances.
Context: On March 6, his first day as secretary, while addressing Housing and Urban Development (HUD) employees, Carson saluted the work ethic of immigrants, and during his comments appeared to compare slaves to voluntary immigrants. A HUD spokesman said that no one present thought Carson "was equating voluntary immigration with involuntary servitude." In the same speech, Carson inaccurately said that the human brain "was incapable of forgetting and could be electrically stimulated into perfect recall."  Under the federal budget proposed by Trump in 2017, HUD's budget for fiscal year 2018 would be cut by $6.2 billion (13%) and the Community Development Block Grant, a program which Carson praised in a trip to Detroit as HUD secretary, would be eliminated. Carson issued a statement supporting the proposed cuts. Carson suggested that federal funds for housing in Detroit could be part of an expected infrastructure bill.  On April 2017, while speaking in Washington at the National Low Income Housing Coalition conference, Carson said that housing funding would be including in an upcoming infrastructure bill from the Trump administration.  In July 2017, during his keynote address at the LeadingAge Florida annual convention, Carson stated his concern about "seniors who become destitute" and reported that the Department of Housing and Urban Development had increased public housing programs for the elderly by an unspecified number.  In the summer 2017, Carson allowed his son, a Baltimore businessman Ben Carson Jr., to participate in organizing a HUD "listening tour" in Baltimore. Internal documents obtained by the Washington Post under the Freedom of Information Act showed that the younger Carson "put people he'd invited in touch with his father's deputies, joined agency staff on official conference calls about the listening tour and copied his wife on related email exchanges." The son's involvement prompted HUD staff to express concern; the department's deputy general counsel for operations wrote in a memorandum "that this gave the appearance that the Secretary may be using his position for his son's private gain." Carson's wife, son, and daughter-in-law also attended official meetings. In February 2018, the HUD inspector general's office confirmed that it was looking into the role that Carson's family played at the department.
Question: What did he do before becoming secretary?

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