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States with an open presidential primary[edit]
Alabama
Arizona (Semi-closed, with primaries open only to unaffiliated or unrepresented voters)
Arkansas
Georgia
Hawaii (Open primary for state, local, and congressional races; caucus system for presidential races.)
Illinois
Massachusetts (All races' primaries open for "unenrolled"/unaffiliated voters only)
Michigan
Minnesota
Mississippi
Missouri
New Hampshire
North Carolina
North Dakota
South Carolina
Tennessee
Texas
Vermont
Virginia
Wisconsin[11]
States with open primaries for other elections[edit]
A similar system known as a nonpartisan blanket primary has been used in Louisiana for state and local elections since 1976, and began to be used in Washington, after numerous court challenges, in 2008.
In California, under Proposition 14, a measure that easily passed, traditional party primaries will be replaced in 2011 with wide-open elections. Proposition 14, known as the open primary measure, will give every voter the same ballot in primary elections for most state and federal races, except the presidential contest.[12][13]