No TM Registration, No Cry

Dear Rich: If you don't have a federal registration, can you still have a trademark? When we started working as an attorney, one of the first jobs we got was working for a trademark attorney on a big case involving two restaurants. We had recently come out of law school after studying with the most excellent J. Thomas McCarthy and were excited to be working on trademark litigation. One afternoon we confided our excitement to the senior attorney who dismissed our comments with a wave of his hand. "Trademark law is bullshit," he said as he handed us another carton of documents to examine. It's been 25 years since we were told that pearl and we're still not sure we fully understand its implications. Was the guy just a jaded mouthpiece, tired of the irrationality and unpredictability of trademark litigation. Or did he hit the nail on the head? We bring this up now because we just re-read our answer, below and wonder if it has an unappealing odor, or whether we're offering practical advice. (BTW, that's what we're all about here at the Dear Rich Headquarters -- providing practical advice!)
Right, you had a question. The short answer is, yes, you can have a trademark even if it is not federally registered. Every state (and the federal government) recognizes rights in trademarks that are not registered (sometimes referred to as "common law trademarks"). Often, someone who is claiming common law trademark rights uses a little "TM" or "SM" (for service mark); the ® symbol can only be used if the mark is federally registered.
Trademarks 101. As a general rule, a business obtains trademark rights once it uses it in a commercial context--that is, the first to associate the mark with a product or service. After the first use, the owner may be able to prevent others from using it, or a similar trademark, for their goods and services as long as the owner continues to use the mark in connection with its goods and services. The rights of the trademark owner, particularly for a trademark that is not registered with the federal government, may be limited by the geographic extent of the use.  
So, if you have a trademark, why register? Registering a trademark or service mark with the USPTO makes it easier for the owner to protect it against would-be copiers and puts the rest of the country on notice that the mark is already taken. We explained the rationale for registration better here.