Because. English examples, 1556–1682 (N.E.D.). Much used by children and illiterate people in the U.S.

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1798.  [He] said so to make fun of me, cause I was a Jarzyman.—The Aurora (Phila.), Dec. 13.

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1816.  Cause you’ve got 20, or 30,000 dollars, you call it a glorious treaty.—Mass. Spy, May 1.

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1856.  Do you eat johnny cake? ’cause if you don’t I’ll cut some wheat bread.—Whitcher, ‘The Widow Bedott Papers,’ No. 7.

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1884.  Harper’s Magazine. (N.E.D.)

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