To change view, select desired zoom level and window size from the options below the Zoom View window and then click on the image. The display will be centered where you click. To move up, down, left, or right within a zoom level, click near the edge of the image in the Zoom View or select an area in the Navigator View. The red box on the Navigator View indicates the area of the image being viewed in the Zoom View.

CREDIT: Lewis, Samuel. "A map of Lewis and Clark's track, across the western portion of North America from the Mississippi to the Pacific Ocean: by order of the executive of the United States in 1804, 5 & 6 / copied by Samuel Lewis from the original drawing of Wm. Clark ; Saml. Harrison, fct.." 1814. Map Collections: 1544-1999, Library of Congress.