In a statement, Simpson, a member of the National Center for Transgender Equality's board of directors, said that "as one of the first transgender presidential appointees to the federal government, I hope that I will soon be one of hundreds, and that this appointment opens future opportunities for many others."
While Simpson is clearly one of the first transgender presidential appointees, Democratic officials say they're unsure if she is the very first one.
The White House had no comment on her appointment.
A 2004 YWCA "Woman on the Move " Simpson recently served as Deputy Director in Advanced Technology Development at Raytheon Missile Systems in Tucson, Arizona.
At Raytheon, Simpson -- a former test pilot who had worked for the company for more than a generation -- transitioned from male to female and was instrumental in convincing the military contractor to add gender identity and expression to its equal employment opportunity policy.
She later ran unsuccessfully for the Arizona House of Representatives and was a delegate for then-Sen. Hillary Clinton, D-NY, to the Democratic National Convention in 2008.