La Ni¿a events typically bring dry conditions to the southwestern United States. Recent La Ni¿as rarely exceed 2 years duration, but a new record of ENSO from a central Pacific coral reveals much longer La Ni¿a anomalies in the 1800s. A La Ni¿a event between 1855--63 coincides with prolonged drought across the western U.S. The spatial pattern of this drought correlates with that expected from La Ni¿a during most of the La Ni¿a event; land-surface feedbacks are implied by drought persistence and expansion. Earlier periods also show persistent La Ni¿a-like drought patterns, further implicating Pacific anomalies and surface feedbacks in driving prolonged drought. An extended index of the Pacific Decadal Oscillation suggests that extratropical influences would have reinforced drought in the 1860s and 1890s but weakened it during the La Ni¿a of the 1880s.