Does your wallet contain an airline-branded credit card? If so, your daily Starbucks visits, iTunes selections, and dining habits serve a critical role in keeping the U.S. airline industry fat and happy. For carriers such as American Airlines riding Citigroup Inc. plastic, or Delta on American Express Co., these programs are a cash cow, a golden goose, or any other fiscal livestock you care to conjure. Each mile fetches an airline anywhere from 1.5 cents to 2.5 cents 1 , and the big banks amass those miles by the billions, doling them out to cardholders each month. For the banks, people who pay annual fees for those cards to accumulate miles are the closest thing to a sure bet. These consumers typically have higher-than-average incomes and spend more on their cards, which generates merchant fees for the banks. They also tend to maintain high credit scores, which means they pay their bills on time and banks experience fewer defaults. Get the full story at Bloomberg