Born in Philadelphia to Thomas Pascal and Mary Louise (Baker) Roberts, William M. Roberts would die in Soledade, Brazil where he had become chief engineer for public works in 1879. Having studied architecture with
John Haviland and at the Franklin Institute, Roberts then embarked on a long career associated with railways and canals, beginning with his part in the construction of the Union Canal in Pennsylvania.
Roberts joined the American Society of Civil Engineers in 1870 and served as vice-president from 1873 to 1878, director in 1876, and president in 1878.