Richard Stengel reviews The Cause: The American Revolution and Its Discontents, 1773-1783, by Joseph J. Ellis, and Power and Liberty: Constitutionalism in the American Revolution, by Gordon S. Wood, at The New York Times.
"Ellis and Wood note that the model for that federal constitution came not from Madison’s imagination but from the laboratories of the states. By the end of 1776, eight states had created their own constitutions with the same separation of powers — executive, legislative, judicial — that the federal constitution would establish. All of them had genuine voter representation, an idea that seems natural today but was radical then."
See American State Papers in Great Books of the Western World (first edition, 52 Vol., 1952) volume 43, (second edition, 60 Vol., 1990) volume 40.