Applicant applied to register SNOW BY REPUBLIC for clothing.  The TTAB approved the registration this mark despite the existence of the following trademark registration for similar clothing items:

SNÖ
In reaching its decision, the TTAB discusses two interesting tenets of trademark law.

FIRST.  A “crowded” field is often used to describe a situation where a common term, in this case “snow,” has been incorporated into numerous trademark registrations for clothes.  In this context, it is usually sufficient to add one additional unique term to the “crowded” field term when trying to secure a registration.  

Submitting unrelated third party registrations as evidence to establish a “crowded” field is the best way to do this.  While registrations are not evidence of use of the identified trademarks in the marketplace, the TTAB does view valid third-party registrations as evidence demonstrating that the addition of various unrelated terms to SNOW and/or variations of “snow” has been sufficient in the past for the USPTO to view the registered marks as sufficiently different from one another as not to cause a likelihood of confusion.  

SECOND.  While certainly not always sufficient, adding one’s undisputed strong house trademark to a disputed sub-brand does tend to reduce the likelihood of confusion between the sub-brand and a cited registration similar to the sub-brand.  

In this case, REPUBLIC was the Applicant’s house brand and SNOW was the disputed sub-brand.  Combining the terms to form SNOW BY REPUBLIC is almost always sufficient when the context of the sub-brand (i.e., “snow” in this case) is a “crowded” field.  
While not mentioned in this case, the addition of well-known house brand can reduce the likelihood of confusion even when the sub-brand is not in a “crowded” field, especially if the trademark is stylized, as opposed to a standard word mark.