Yellowstone National Park

Yellowstone National Park, a high-lying tract of land in the State of Wyoming (q.v.) traversed by the Yellowstone, about the size of Kent, being a square about 75 m. in diameter; is set apart by Congress as a great pleasure ground in perpetuity for the enjoyment of the people; it abounds in springs and geysers, and care is taken that it be preserved for the public benefit, to the exclusion of all private right or liberty.

Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)

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Yankee
Yapura
Yarkand
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Yarrell, William
Yarrow
Yates, Edmund
Yeddo
Yellow Sea
Yellowstone, the
Yellowstone National Park
Yemen
Yenikale
Yenisei
Yeniseisk
Yeomanry
Yeomen
Yeomen of the Guard
Yeovil
Yetholm
Yezd