Governor Greg Abbott allowed businesses including hair salons to reopen from early May, with gyms and swimming pools allowed to reopen from May 18.
Figures from the most recent day, June 9, show the state reported 1945 new cases, up from 445 on May 25. Yesterday, the state also reported record numbers of virus-related hospitalisation rates for the third consecutive day, with 2153 patients in hospital. Hospitalisations have now risen by 42 per cent since Memorial Day.
At the weekend, Florida reported 1426 new cases, its highest number since early April. Governor Ron DeSantis has played down suggestions that the spike is linked to his early efforts to reopen businesses, instead pointing to higher testing rates.
Officials in California, which began reopening in early May and has reported record numbers of new cases in recent days, said family gatherings such as birthday parties and funerals were driving the increase.
Dr Olivia Kasirye, the health officer for Sacramento County, said that despite state orders banning such gatherings, the reopening of restaurants, shops and hair salons had given a false sense of safety.
It comes as demonstrators have taken to the streets ignoring social distancing to protest against police brutality, sparking fears the number of new cases could rise higher still.
Dr Anthony Fauci, America's top infectious disease expert, said: "It's a perfect set-up for further virus spread."