The previous record was 1.03 million cases on January 3. A large number of cases are reported each Monday due to many states not reporting over the weekend. The seven-day average for new cases has tripled in two weeks to over 700,000 new infections a day.
Not all states have yet reported on Monday and the final figure is likely to be even higher.
The record in new cases came the same day as the nation saw the number of hospitalised COVID-19 patients also hit an all-time high, having doubled in three weeks, according to a Reuters tally.