Delta hikes rates, other carriers follow ATLANTA, Jan. 13 (UPI) -- Delta Airlines' move to hike domestic fares this week prompted its U.S. competitors to follow suit, bringing the first round of increases this year. On routes longer than 1,500 miles, Delta's rate went up $10 higher each way Wednesday. United-Continental Airlines, American Airlines and US Airways matched the increase on long domestic flights the next day. Low-cost carriers Southwest-Air Tran and Frontier Airlines also raised their prices, USA Today reported. Fare increases often do not last, as carriers try not to price themselves too high above competitors, but a low-cost carrier going along is an indication the hike could stick. We're still battling high fuel prices. Any kind of increase we take is specifically to combat the high cost of fuel," said Southwest spokeswoman Katie McDonald. Airlines successfully raised prices in the first half of last year while reducing the number of flights, leading to increased demand for seats. Mergers of airlines have also reduced competition between carriers.