Because I see so many people who believe otherwise, here's a direct quote from a prior contract:

> I UNDERSTAND AND ACKNOWLEDGE THAT MY EMPLOYMENT WITH THE COMPANY IS FOR NO SPECIFIED TERM AND CONSTITUTES "AT-WILL" EMPLOYMENT. I ALSO UNDERSTAND THAT ANY REPRESENTATION TO THE CONTRARY IS UNAUTHORIZED AND NOT VALID UNLESS SIGNED BY THE PRESIDENT OR CEO OF THE COMPANY. ACCORDINGLY, I ACKNOWLEDGE THAT MY EMPLOYMENT RELATIONSHIP MAY BE TERMINATED AT ANY TIME, WITH OR WITHOUT GOOD CAUSE OR FOR ANY OR NO CAUSE, AT MY OPTION OR AT THE OPTION OF THE COMPANY WITH OR WITHOUT ME NOTICE. I FURTHER ACKNOWLEDGE THAT THE COMPANY MAY MODIFY JOB TITLES, SALARIES, AND BENEFITS FROM TIME TO TIME AS IT IS NECESSARY.

Every job I ever held but the unionized ones had some variation of that.