My entire working life (>20 years) I've always been forced to sign an agreement that I was an employee "at will" and either myself or the company could terminat

My entire working life (>20 years) I've always been forced to sign an agreement that I was an employee "at will" and either myself or the company could terminate employment at any time for any reason or no reason at all. Absent membership in a union, I assume she signed a similar agreement, because it's totally standard in the US.