What are my rights if my compensation and ability to be promoted has been effected because I am not personal friends with my district manager?

First off, a hostile workplace environment is one that prevents an employee from doing their job duties reasonably. In such a situation, a boss and/or co-worker creates an environment that is counterproductive due to their behavior and/or actions. However, these behaviors typically must be discriminatory in nature and are not just a result of rude behavior.

Secondly, discrimination is action taken against an employee because they are a member of a "protected class"; in other words race, religion, age, disability, sex, national origin (and in some states gender identity) must not be a factor in their treatment.

Based on the you that you have facts presented, neither seems to have played a role in your situation. It's not clear that you are unable to perforn your work duties due to a lack of friendship with your GM. Additionally, although you may bot be treated the same as other workers, there is no law that says you must be (unless you are a member of a protected class). Consequently, while your treatment may be unprofessional, it is legal.

The fact is that most employment relationships are what is known as "at will". This means that basically an employer can hire/fire someone for any reason or no reason whatsoever, as well has increase/decrease salary/hours, promote/demote, and generally impose the conditions of employment as it sees fit. In turn, an employee can work for an employer or not, their choice. Exceptions to this would be if there is a stated company policy prohibiting such behavior, or there is a union/employment agreement to the contrary, or (as stated above) if the situation has arisen due to some type of discrimination.