I am sorry to hear about what you went through. If you believe racism is going on I strongly suggest you file a complaint with the Department of Transportation. That is illegal not to mention unethical. It will help to have the agent's name and description. I agree that is not right.
http://airconsumer.ost.dot.gov/problems.htm
Also, I am not familiar with the airport in which this happened but I do know many airports have large screens displaying the departure gate of given flights. And you can also call 1-800-252-4444 if you know your flight number and the machine will tell you current flight status as well as departure gate.
I tell this to all passengers so please don't feel like I am singling you out. It is important to get to the airport early in case their is a long line. It sounds like you were at the airport just barely in time. Glad you made the flight in time.
I hope my info helps.