Research Group, and its leader, Joseph P. Williams. Williams convinced senior BofA executives in 1956 to let him pursue what became the world's first successful mass mailing of unsolicited credit cards (actual working cards, not mere applications) to a large population. Williams' pioneering accomplishment was that he brought about the successful implementation of the all-purpose credit card (in the sense that his project was not canceled outright), not in coming up with the idea. By the mid-1950s, the typical middle-class American already maintained revolving credit accounts with several different merchants, which was clearly inefficient and inconvenient due to the need to carry so many cards and pay so many separate bills each month. The need for a unified financial instrument was already evident to the American financial services industry, but no one could figure out how to do it. There were already charge cards like Diners Club (which had to be paid in full at the end of each billing cycle), and "by the mid-1950s, there had been at least a dozen attempts to create an all-purpose credit card." However, these prior attempts had been carried out by small banks which lacked the resources to make them work. Williams and his team studied these failures carefully and believed they could avoid replicating those banks' mistakes; they also studied existing revolving credit operations at Sears and Mobil Oil to learn why they were successful. Fresno was selected for its population of 250,000 (big enough to make a credit card work, small enough to control initial startup cost), BofA's market share of that population (45%), and relative isolation, to control public relations damage in case the project failed. According to Williams, Florsheim Shoes was the first major retail chain which agreed to accept BankAmericard at its stores. The 1958 test at first went smoothly, but then BofA panicked when it confirmed rumors that another bank was about to initiate its own drop in San Francisco, BofA's home market. By March 1959, drops began in San Francisco and Sacramento; by June, BofA was dropping cards in Los Angeles; by October, the entire state of California had been saturated with over 2 million credit cards and BankAmericard was being accepted by 20,000 merchants. However, the program was riddled with problems, as Williams (who had never worked in a bank's loan department) had been too earnest and trusting in his belief in the basic goodness