Thursday marks the 90th anniversary of Social Security. The monthly payments are a lifeline for millions of Americans, but after years of cash flow problems, drastic changes could be around the corner if Congress doesn't act.

When President Franklin D. Roosevelt signed the Social Security Act in 1935, the law was designed to keep seniors out of poverty. Since then, Congress repeatedly voted to expand Social Security. Today, it's available to almost all Americans.

"Very different from how the program was originally sold as an anti-poverty program, it is now primarily an income replacement program for working Americans, regardless of need," explained Romina Boccia, the director of budget and entitlement policy at the Cato Institute.

The calculation to determine someone's monthly payment i

See Full Page