The US Transportation Security Administration screened 1.64 million passengers on Thursday at US airports, the highest number since March 2020, when the coronavirus pandemic slashed travel demand. The number of US air travellers is still about 35 per cent lower than the same date in 2019, down nearly one million travellers, the TSA said. Airlines in the country have been adding more flights, anticipating rising summer travel demand. US airline stocks rose on Friday, on optimism about travel demand, with United Airlines up 2.3 per cent, American Airlines up 2 per cent and Delta Air Lines up 2.3 per cent. This is the second new post-March 2020 high set this week. TSA said it screened nearly 1.63 million passengers on Sunday at US airports. By comparison, only 190,000 people were screened at US airports on the same day in May 2020. Last month, United Airlines said it was adding more than 480 daily flights to its schedule in June to meet summer travel demand that is expected to rise as more people receive Covid-19 vaccines. American Airlines said in April it expects to fly more than 90 per cent of its domestic seat capacity compared with summer 2019 and 80 per cent of its international seat capacity compared with 2019. It will also operate more than 150 new routes this summer. Airlines are experiencing an uptick in bookings as accelerated <a href="https://www.thenationalnews.com/world/europe/eu-set-to-allow-vaccinated-us-tourists-to-visit-this-summer-1.1210756">vaccination efforts encourage leisure travel</a> with friends and family after months of pandemic-linked restrictions. The US domestic market, unfettered by border restrictions, should <a href="https://www.thenationalnews.com/business/travel-and-tourism/where-can-you-fly-right-now-americans-jet-south-to-caribbean-beaches-1.1218159">return to almost normal levels by July,</a> said travel data provider OAG.