July 17 (Reuters) - For a second day in a row, U.S. coronavirus cases rose by over 70,000 as Americans clashed over wearing masks and whether to reopen schools in a few weeks.

Cases on Friday rose by at least 70,674 after climbing by a record 77,499 on Thursday, the largest increase posted by any country since the pandemic started, according to a Reuters tally.

U.S. deaths on Friday rose by at least 912, the fourth day in a row that fatalities have risen by over 900 a day.

(Writing by Lisa Shumaker. Editing by Gerry Doyle)