Interesting, here's an article with many comments about where McDonalds hamburgers come with mustard and where not: http://aht.seriouseats.com/archives/2010/03/dear-aht-differences-in-regional-mustard-use-on-mcdonalds-hamburgers.html Long Island - no New Jersey - yes Boston - yes Texas - yes Wisconsin - yes Bay Area - yes SoCal - yes Northwest - yes (though see the Portland comment above) This struck me as revealing: "I grew up in New York but we would frequently drive to visit relatives in Pittsburgh, and we were forever trying to pinpoint the exact line on I-76 when mustard started appearing on the burgers." and "I can definitely confirm mustard on every McDonalds burger I've ever had outside of NYC and my native Long Island, including NJ, CT and Upstate NY. States in which I've eaten McDonalds include: NJ, CT, RI, MA, ME, PA, DE, NC, SC, GA, FL, AL, MT, WY, CA and SD. Every last one of them had mustard. I concur with my fellow Islanders: mustard is in every way anathema to a NYer on a burger." Obivously I cannot hang with that last statement, but then I grew up in Massachusetts so what do I know!