That depends entirely on what state you are in and what your company policy says.
In some states, unused vacation must be paid out, unconditionally.
In some states, unused vacation never has to be paid out.
In some states, unused vacation only has to be paid out if there is a company policy saying they will.
In some states, unused vacation has to be paid out unless a company policy says they will not.
If you post your state, I can tell you which category your state falls into.