Trademark protection in the United States dates back to colonial times when American common law recognized some intellectual property rights. This tradition has its traces in history, because many American companies live from their marketing strategies. These companies understand the importance of registering and protecting their trademark to promote their brand.
Because of this, registering a trademark in the US is a fairly quick and cheap process compared to other countries, and even unregistered trademarks can enjoy some legal protection if they have already been used in commerce. If so, you must be able to show that your use of the mark is well established in your interstate business. This is not always easy to prove and it is not economical to hold your own against your competitor if you have skipped the registration phase of your trademark.
At the federal level, the United States Patent and Trademark Office (USPO) administers trademark registration in the United States. Because of the legal value of commercial use of trademarks, it is possible to enter the American market before applying for registration. Nevertheless, it is also possible and often advisable to file the so-called "intent-to-use" trademark application. You can file an Intent to Use (ITU) application if you submit an affidavit of intent, but be aware (!) that in the event of a lawsuit, you will need to demonstrate your efforts to “commercialize” your mark soon after the application date. Later you should be able to convert the (ITU Application) to the ordinary (Use-in-Commerce Application) using a set of specific procedures.
Before any filing, it is important to conduct a thorough research for possible trademarks that could be confused with yours. Attention! This research is the responsibility of the applicant. USPO offers a search system (Trademark Electronic Search System, TESS) that can be used for this search, but it must be noted that the search engine does not consider trademarks that are not registered at the federal level but are used in commerce that differ can even assert themselves against registered ones.
Descriptive marks can only be protected (so-called weak protection) if they are considered distinctive due to their commercial use for more than 5 years. The federal agency sets strict parameters to assess the class of products or services to which your trademark relates. To avoid confusion or many other grounds for refusal that the Office may find, you should consider seeking legal advice.