Dr. Ron Tyler returned to the Amon Carter in 2006 as director. (Dr. Tyler began his museum career at the museum from 1969 to 1986.) During his tenure as director, the museum presented major exhibitions of the work of Alfred Jacob Miller (1810–1874) and William Ranney (1813–1857), and an important exhibition of African-American art from the private collection of Harmon and Harriet Kelley. Paintings by George de Forest Brush (1855–1941) and Charles Sheeler (1883–1965), as well as a complete, 20-volume set of Edward Sheriff Curtis’ "The North American Indian" (1907–1930), were added to the museum’s permanent collection during Dr. Tyler’s administration. Dr. Andrew J. Walker has led the Amon Carter since 2011. Under Dr. Walker's leadership, the ACMAA has hosted major exhibitions of work by George Caleb Bingham (1811–1879), Will Barnet (1911–2012), and the circle of New York modernists led by artist John Graham (1886–1961). He has overseen additions to the permanent collection of works by Robert Seldon Duncanson (1821–1872), Raphaelle Peale (in memory of Ruth Carter Stevenson), and John Singer Sargent (1856–1925), and he initiated major upgrades to the museum’s digital presence, including the "Connecting to Exhibitions" digitization project, a two-year initiative that will allow online access to many of the museum’s previous art exhibitions.