How NBER dates recessions
In the United States recessions are not declared by the government or by a GDP rule — they are dated after the fact by the Business Cycle Dating Committee of the National Bureau of Economic Research, a private research institution whose chronology is the accepted standard.
Not two quarters of GDP
The popular 'two consecutive quarters of negative GDP' shorthand is a rule of thumb, not the definition. The committee weighs a basket of monthly indicators — employment, real personal income, industrial production, wholesale-retail sales, real manufacturing-and-trade sales — looking for a decline that is significant, persistent, and broad-based across the economy.
Why the calls are late
Official announcements arrive 4–21 months after the fact: the committee prefers accuracy over speed, waiting for revisions and for the trend to become unambiguous. The 2020 recession was declared in June 2020 — already over by then (it ended in April). This inherent delay is precisely why real-time signal monitoring exists: by the time NBER speaks, the episode is usually history.