Prevailing wage
A prevailing wage law requires that workers on public construction be paid no less than the locally prevailing wage for their classification. At the federal level that is the Davis-Bacon Act; many states add their own prevailing wage law for state- and locally-funded projects (sometimes called a "little Davis-Bacon" law).
Federal: the Davis-Bacon Act
The Davis-Bacon Act requires payment of locally prevailing wages and fringe benefits to laborers and mechanics on federal construction contracts over $2,000. It applies to federal contracts no matter which state the project is in. See 40 U.S.C. § 3141–3148 and the Department of Labor's implementing regulations at 29 CFR Parts 1, 3, and 5.
State prevailing wage laws
A number of states have their own prevailing wage laws for state and local public projects. These are separate from Davis-Bacon and have their own thresholds, coverage, and rate-setting. Whether a given state has such a law — and what it covers — is a fact to be confirmed against that state's statute, not assumed from the federal rule.
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