Splawn was an Arlington, Texas, native, born to William Butler and Mary Marshall (Collins) Splawn on June 16, 1883. He graduated from Baylor University in 1906 with a bachelor's of arts degree. Splawn taught at his alma mater from 1910 to 1912, then began the practice of law in Fort Worth, Texas. He earned a master's of arts degree at Yale University in 1914, and returned to teach at Baylor in 1916. In 1919, Splawn joined the University of Texas at Austin faculty. While teaching economics in Austin, Splawn completed a doctorate at the University of Chicago in 1921. In 1923, Splawn was appointed to the Railroad Commission of Texas by Pat Morris Neff. The next year, Splawn was selected to succeed interim William Seneca Sutton as president of the University of Texas at Austin, though he was the second choice of the University of Texas Board of Regents. After leaving Austin in 1928, Splawn served as dean of the graduate school of American University, in Washington, D.C., between 1929 and 1934.
