1) The most-watched television event in the United States is the Super Bowl, with millions of viewers tuning in each year.

2) The Federal Reserve System, often referred to as the Fed, is the central banking system of the United States.

3) The oldest known musical instrument is a flute made from a bird bone, estimated to be around 43,000 years old.

4) The concept of proportional representation, used in some electoral systems, aims to ensure that political parties' representation in government aligns more closely with the proportion of votes they receive from the electorate.