westward movement frontier american definition history painting britannica jackson south
acquisitions territorial gains louisiana river mississippi unis westward etats territories geographic gained treaty britain oregon 1846 nationalgeographic mapporn mapa boundary
landward coastal boundaries hinterland
coastal hinterland boundaries landward
coastal adaptive salty urbanism framework rise towards address level sea figure
waters noaa lakes unmapped extent survey mapping geographic
convention expanding ceded worldatlas reasons settlement 1840s colonized everett collection