The USPTO is not responsible for stopping others from infringing your mark. In the United States, trademark owners are responsible for protecting their rights in their marks.
What to Monitor
Monitor USPTO filings. Although the USPTO Examining Attorney will conduct a search of the USPTO database for conflicting marks before allowing a new mark to be registered, sometimes they allow marks to proceed that you may believe will cause confusion with your mark.
State Registers and Directories. Other places to monitor are State registers, business directories, and the market in general. Monitoring for conflicting use is not mandatory but good practice.
Why Monitor?
The longer you use your mark and the more widely known it becomes, the more valuable it becomes. That value is generally referred to as your company’s goodwill. It is your business reputation for the quality of your goods and services.
Confusion
If someone decides to compete with you selling similar goods and services and chooses to use a mark that is very similar to your mark, customers may be confused and buy your competitor’s goods and services thinking they are yours.
Infringement
The possible confusion in the minds of customers over the source of goods and services stemming from the similarity of the marks raises trademark infringement issues.
Dilution
Once you realize confusion is occurring, it is important to take steps to protect your mark. Failure to enforce your rights against others will ultimately weaken your rights and impair your mark’s value. However, before contacting the other user, it is important to confirm as best you can that the other user commenced use of the mark AFTER you did. Even if you have a USPTO registration and the other user does not, if the other user commenced use BEFORE you, there is a chance that the other user could cancel your registration and force you to use a different mark.
Assessment:
DO NOT WAIT AND HOPE THE OTHER USER GOES AWAY! If you discover a competitor using a mark that you believe may be causing confusion, seek professional assistance to assess the situation and determine how to best proceed.