prairie schooner

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A covered wagon, drawn by horses or oxen, that was used by pioneers in crossing the North American prairies and plains.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A horse-drawn wagon used to transport people and goods in the American west of the 18th and 19th centuries.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a large wagon with broad wheels and an arched canvas top; used by the United States pioneers to cross the prairies in the 19th century