• Looking back at the stories to remember from the past week:
• . "POLAR VORTEX" GRIPS MUCH OF U.S., BRINGING RECORD LOWS
• On Tuesday, the whirlpool of cold air plunged temperatures into the single digits and teens from Boston and New York to Atlanta, Birmingham, Nashville and Little Rock -- places where many people don't know the first thing about extreme cold. Authorities reported at least 21 cold-related deaths across the country since Sunday, including seven in Illinois and six in Indiana.
• . CHEMICAL SPILL SHUTS DOWN MUCH OF WEST VIRGINIA CAPITAL
• A chemical spill left the waters in West Virginia's capital tinted blue-green, forcing hundreds of thousands of people to rely on bottled water and stop taking showers and doing laundry. The federal government joined the state in declaring a disaster following Thursday's spill, while federal authorities launched an investigation into how the irritant escaped a chemical plant and seeped into the Elk River. Just how much of the chemical leaked and how long it will take before the water is safe remained unclear.
• . NJ GOV. CHRISTIE FIRES AIDE, SAYS HE KNEW NOTHING ABOUT TRAFFIC JAMS TO PUNISH MAYOR
• Republican Gov. Chris Christie fired one of his top aides on Thursday and apologized repeatedly for his staff's 'stupid' behavior, insisting he had no idea anyone around him had engineered traffic jams as part of a political vendetta against a Democratic mayor. Hundreds of pages of documents subpoenaed by a New Jersey legislative committee investigating the September traffic jams near the George Washington Bridge were released Friday.
• . SENATE CONFIRMS JANET YELLEN TO HEAD THE FEDERAL RESERVE
• Yellen, confirmed by a 56-26 vote Monday, faces a significantly different economic landscape from the one that dominated Ben Bernanke's time as chairman -- a tenure that was largely consumed with the Great Recession and his efforts to cure it by pushing down interest rates and pumping cash into the economy. Many economists think Yellen's big challenge will be deciding how to ease off some of those very policies.

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