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Pre-European Exploration, Prehistory through 1540 European Exploration and Settlement, 1541 through 1802 Louisiana Purchase through Early Statehood, 1803 through 1860 Civil War through Reconstruction, 1861 through 1874

Post-Reconstruction through the Gilded Age, 1875 through 1900 Early Twentieth Century, 1901 through 1940 World War II through the Faubus Era, 1941 through 1967 Divergent Prosperity and the Arc of Reform, 1968–2022

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Hydra

Two species of Hydra. Left: Common hydra, Hydra vulgaris. Right: Carnivorous green hydra, Hydra viridissima.

Tree like organisms under microscope

Public domain

Related Entries

Organisms under microscope with corresponding letters

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Major support provided through a partnership with the Arkansas Department of Parks & Tourism.

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This project is funded in part by a National Endowment for the Humanities (NEH) Sustaining the Humanities through the American Rescue Plan grant award.

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