New York: New York passed a gradual emancipation law in 1799, which freed all children born into slavery after July 4, 1799, at age 28 for males and age 25 for females.
Pennsylvania: Pennsylvania passed a gradual emancipation law in 1780, which freed all children born into slavery after November 1, 1780, at age 28.
New Jersey: New Jersey passed a gradual emancipation law in 1804, which freed all children born into slavery after March 4, 1804, at age 25.
Ohio: Ohio was admitted to the Union as a free state in 1803.
Indiana: Indiana was admitted to the Union as a free state in 1816.
Illinois: Illinois was admitted to the Union as a free state in 1818.
Michigan: Michigan was admitted to the Union as a free state in 1837.
Iowa: Iowa was admitted to the Union as a free state in 1846.
California: California was admitted to the Union as a free state in 1850.
Washington: Washington was admitted to the Union as a free state in 1889.
Montana: Montana was admitted to the Union as a free state in 1889.
Idaho: Idaho was admitted to the Union as a free state in 1890.
Wyoming: Wyoming was admitted to the Union as a free state in 1890.
North Dakota: North Dakota was admitted to the Union as a free state in 1889.
South Dakota: South Dakota was admitted to the Union as a free state in 1889.
Alaska: Alaska was admitted to the Union as a free state in 1959.
Hawaii: Hawaii was admitted to the Union as a free state in 1959.