With confidence rising that the end of the pandemic is growing closer, airlines are starting to revive flights that vanished last year as people cancelled vacations and business trips. United Airlines will add 26 new nonstop routes from Midwest cities to vacation spots like Hilton Head and Portland, Maine. The airline said Thursday that it is also restarting more than 20 domestic routes. Scheduled flights to Latin America will exceed levels before the pandemic, compared with the same stretch in 2019. While that means United will be operating only 52% of its overall schedule compared with May 2019, it’s significantly better than in May 2020, when flights were being operated at levels of about 14% of the same period the year before.