The U.S. credit rating was downgraded by Moody's Ratings on Friday, highlighting investor concerns about the government's growing debt.The downgrade from the top rating of Aaa to Aa1 "reflects the increase over more than a decade in government debt and interest payment ratios to levels that are significantly higher than similarly rated sovereigns,

Decades of excessive spending by Congress has caused Moody's to lower America's credit rating. We'll look at federal revenue and spending over the past 59 years.