DALLAS (AP) — From barbecues to getaways to shopping the sales, many people across the U.S. mark Labor Day — the federal holiday celebrating the American worker — by finding ways to relax. The holiday with activist roots is celebrated on the first Monday of September, creating a three-day weekend that marks the unofficial end of summer. Over 17 million people were expected to travel by air from Thursday through Wednesday, according to the Transportation Security Administration, with Friday being the day with the most travelers.