Can someone help me rephrase this sentence? And is it a good topic sentence to start off with?
The media negatively portrays immigration, as they only cover it when there is a newsworthy story relating to drug violence, and as a result the American public is misinformed.
The word "media" is plural. It refers mainly to newspapers, magazines, and television. So you should say "portray" rather than "portrays." But may you shouldn't say "negatively portray immigration" at all. It sounds like an extreme accusation. It makes it seem as if the media have an ulterior motive, when at the same time your sentence suggests that they are only interested in newsworthy stories. I suggest that your thesis sentence might read something like the following:
The media keep the American public misinformed about immigration because they naturally tend to focus on sensational stories which often involve drug-related violence.
I don't feel that you are mainly interesting in attacking the media--at least in this essay. You seem more interested in stating what you believe to be the real truth about immigration. Therefore, you probably shouldn't start off by sounding as if you are going to attack the media. It is understandable that they would focus on what you call "newsworthy stories." You can dispose of the media in the first sentence and go on to explain what are the facts about immigration that tend to get overlooked.
I hope this is helpful.