Flew from DCA-AMS via PHL on November 1st. AA5171 arrived in PHL about 8:04PM and my small checked bag was offloaded at 8:07PM. My connecting flight AA204 departed PHL at 10:00PM but WITHOUT MY BAG!. The weather was mild and the airport was calm on that midweek, evening, yet AA couldn't transfer my bag in NEARLY TWO HOURS. In fact, they made no effort to expedite the bag via other carriers but routinely loaded it on AA204 the next day after I flagged their oversight to them. I wrote to Mr. Sean Bentel and got a standard form letter type apology and $125 credit voucher almost immediately, but no explanation as to why my priority-tagged bag was "forgotten" at PHL nor any positive steps AA is taking to ensure this won't happen again. As a Platinum member who has experienced three baggage snafus at PHL in recent years, I believe more needs to be done then just sending out evouchers so customers can repeat their miserable experience. An airline that cannot transfer a simple bag with tags intact in two hours is not worthy of my business.