The holiday travel season has begun and officials at Louisville International Airport are expecting crowds. But travel habits have changed over the years.Airport spokesperson Trish Burke says many travelers now extend their holiday trips—leaving earlier and returning later than in years past."That's in response to the airline pricing, which encourages lower prices for different times, typically non-peak times," she says.Burke says the regular advice to arrive early and pack light for holiday flights still stands.This is not the busiest time for travel at Louisville International. Burke says the crowds are heaviest during Derby week.