New Haven, Connecticut becomes the first United States city to give identification cards to undocumented immigrants.
- Voters in the U.S. states of Connecticut, Delaware, Maryland, Pennsylvania and Rhode Island head to the polls to vote in Democratic and Republican presidential primaries.
- February 2013 nor'easter: The death toll from a massive blizzard across the Northeastern United States and southeastern Canada rises to at least 15, with 40 inches of snow reported from Hamden, Connecticut. More than 900,000 customers lost power at the height of the storm, while airports in the region cancelled over 5,300 flights.
- A shooting at Sandy Hook Elementary School in Newtown, Connecticut, United States, leaves 28 people dead, including 20 children, the shooter, and his mother.
- A worker kills 9 people, including himself, in a workplace incident at Hartford Distributors Inc in Connecticut, United States.
- The Nobel Prize committee awards American Richard Thaler the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel "for his contributions to behavioral economics." His work focuses on the psychology of the human conflict of what we plan for the financial present versus what we plan for the future.