Southwest Airlines (NYSE:LUV) known for its cheap domestic flights, is now going international. The airline plans to start making international flights for the first time with its move to start offering former AirTran’s routes to Mexico and the Caribbean. The company is looking to add as many as 25 flights a day.This would require the opening of a new terminal at Houston’s William P. Hobby Airport which will cost between $100- $125 million. Starting international flights for the first time was most likely a reason why Southwest decided to buy AirTran last year for $1 billion. The opening of the new terminal will bring roughly 1.5 million more passengers annually to the Houston airport as well as create 10,000 jobs and bring in about $1.6 billion a year.Southwest stock climbing on the news. Shares are currently 2.5% higher at $8.57.