People spend their Sunday afternoon on the National Mall in Washington D.C., the United States, on June 28, 2020. More than 2,531,000 COVID-19 cases have been reported in the United States with the fatalities surpassing 125,600 as of Sunday afternoon, according to a tally by Johns Hopkins University. (Photos: Xinhua)

People spend their Sunday afternoon on the National Mall in Washington D.C., the United States, on June 28, 2020. More than 2,531,000 COVID-19 cases have been reported in the United States with the fatalities surpassing 125,600 as of Sunday afternoon, according to a tally by Johns Hopkins University.

People tour around the Lincoln Memorial Reflecting Pool on the National Mall in Washington D.C., the United States, on June 28, 2020. More than 2,531,000 COVID-19 cases have been reported in the United States with the fatalities surpassing 125,600 as of Sunday afternoon, according to a tally by Johns Hopkins University.

People ride scooters around the Lincoln Memorial Reflecting Pool on the National Mall in Washington D.C., the United States, on June 28, 2020. More than 2,531,000 COVID-19 cases have been reported in the United States with the fatalities surpassing 125,600 as of Sunday afternoon, according to a tally by Johns Hopkins University.

People spend their Sunday afternoon on the National Mall in Washington D.C., the United States, on June 28, 2020. More than 2,531,000 COVID-19 cases have been reported in the United States with the fatalities surpassing 125,600 as of Sunday afternoon, according to a tally by Johns Hopkins University.

People spend their Sunday afternoon on the National Mall in Washington D.C., the United States, on June 28, 2020. More than 2,531,000 COVID-19 cases have been reported in the United States with the fatalities surpassing 125,600 as of Sunday afternoon, according to a tally by Johns Hopkins University.