PolkBy: Walter R. Borneman In Polk, Walter R. Borneman gives us the first complete and authoritative biography of a president often overshadowed in image but seldom outdone in accomplishment. James K. Polk occupied the White House for only four years, from 1845 to 1849, but he plotted and attained a formidable agenda: He fought for and won tariff reductions, reestablished an independent Treasury, and, most notably, brought Texas into the Union, bluffed