Three ways that American not allowed to vote?

Race, color, or previous condition of servitude" (15th Amendment, 1870)

"On account of sex" (19th Amendment, 1920)

"By reason of failure to pay any poll tax or other tax" for federal elections (24th Amendment, 1964)

If your a felon, if your under 18, and if your havn't been a permanent resident for more than 5 years (3 if your married to a U. S. citizen)