California’s governor announced Monday that the state is “pulling the emergency brake” on its reopening and reinstating broad restrictions, while Iowa’s governor reversed course and announced a mask mandate.The announcements came as the United States reported its 11 millionth confirmed case on Sunday, with one million new cases over the past week alone. The country is averaging 150,000 new cases a day and will probably reach 250,000 total deaths sometime this week.- Advertisement – The increases, he said, cross age and racial or ethnic groups and appear throughout the state.- Advertisement – – Advertisement – Most of California’s larger counties were moved back into the most restrictive reopening tier, meaning that indoor dining and some other businesses would have to shut down again. Mr. Newsom said the state was also studying curfew options.Mr. Newsom added that emergency health care facilities the state set up during the beginning of the pandemic were being prepared. One facility will open in the next week or so in Imperial County, a border county that was hit hard over the summer, he said.State leaders including Mr. Newsom have told residents not to gather with people from outside their households, and to resist visiting relatives over the holidays.- Advertisement – The gathering on Nov. 6 did not technically violate the state’s rules, because there is no formal limit on the number of households at each outdoor restaurant table, but as critics noted, the governor’s attendance undermined the spirit of restrictions.Mr. Newsom apologized on Monday, saying that he should have turned around and left when he realized there were more guests at the party than he expected. Much of the recent rise in cases, state officials say, appears to have grown from at-home parties or family gatherings.But in what is likely to be remembered as one of the governor’s more damaging moments in the pandemic, The San Francisco Chronicle reported that Mr. Newsom attended an outdoor dinner for one of his political advisers at the French Laundry, a Napa Valley restaurant, with guests from several households. Daily case reports are rising in 48 states, and with little action from the Trump administration, governors and mayors across the country are taking new steps to try to halt the spread. On Monday, a sweeping stay-at-home advisory went into effect in Chicago, and Philadelphia announced strict new rules starting Friday, banning indoor gatherings and closing indoor dining at restaurants.In California, which had been credited with getting the virus under control for a time, Gov. Gavin Newsom, a Democrat, said the state’s daily case numbers had doubled in the last 10 days, the fastest increase the state had seen since the beginning of the pandemic. The state reached one million known cases on Nov. 12, and the next day issued travel advisories.