[4] After his father, a physician educated at the Medical College of Philadelphia and a medical officer in the Carolina Dragoons, was killed in the American Civil War, Miller left for Washington, D.C. As a young boy, Miller worked there as a printer's devil for the Washington Post, and later worked as a page in the United States Senate, meeting many national leaders of the era.

Eventually, Miller traveled west to Dallas, where he studied law in the firm of Robertson & Coke.

Miller was a lawyer and was elected as a Democratic Texas state Senator in 1899 representing Dallas County.

In 1911, he was appointed a Judge of the Criminal District Court in Dallas County and Miller was reelected in 1915.

In 1930, Miller was unsuccessful candidate for Governor of Texas, losing the Democratic nomination in a very crowded field to Houston oilman Ross Sterling.