American Infrastructure Opportunity Bonds Act This bill directs the Department of the Treasury, when the real rate (the interest rate on outstanding marketable U.S. obligations with remaining maturity periods of approximately one year minus the inflation rate) equals zero percent or less, to: issue government bonds (American Infrastructure Opportunity Bonds) with a face value of $20 billion; and deposit amounts equivalent to the proceeds from such issuance into the Highway Trust Fund (HTF), of which 20% shall be deposited into the Mass Transit Account.