The modern system of initiative and referendum originated in the U.S state of Oregon in 1902 when legislators voted overwhelmingly in favor of it. This idea, originally known as the "Oregon System", has since spread to 23 other states.

Some well-known examples of initiatives are various ballot measures or propositions enacted by voters in states such as Oregon and California, such as California Proposition 13 (1978), which limited real estate tax rates.

An initiative differs from a referendum in that a referendum gets submitted to voters by a vote of a legislature, while an initiative can be placed on the ballot in another way, often by obtaining a sufficient number of signatures on a petition. The availability, if any, of an initiative or referendum process varies from state to state (or political jurisdiction).

See also: recall.