{"title": "Westward expansion", "covers": [4380962], "subject_places": ["United States", "Mississippi River Valley", "West (U.S.)"], "first_publish_date": "1949", "key": "/works/OL3577032W", "authors": [{"type": {"key": "/type/author_role"}, "author": {"key": "/authors/OL603912A"}}], "subject_times": ["1803-1865"], "type": {"key": "/type/work"}, "subjects": ["Territorial expansion", "Frontier and pioneer life", "History", "United states, territorial expansion", "United states, history", "Mississippi river valley, history", "West (u.s.), history", "History of the American frontier"], "description": {"type": "/type/text", "value": "Discusses the colonial frontier, the trans-Appalachian frontier, the trans-Mississippi frontier. The geographic continuity is stressed."}, "latest_revision": 9, "revision": 9, "created": {"type": "/type/datetime", "value": "2009-12-10T03:53:57.178403"}, "last_modified": {"type": "/type/datetime", "value": "2023-12-14T20:46:45.714605"}}