On a regular basis the United States Patent and Trademark Office publishes a magazine with newly approved trademarks. The publication is free and open to the public for review.
One reason for making this publication is so members of the public have an opportunity to object. There are a multitude of reason to oppose the issuance of a trademark. This can be done if you, as the opposer, will be harmed by the issuance of a trademark.
The official gazette is here at the USPTO’s website.