Yes, they are. I live less than 10 miles north of the Rio Grande and we pick up all of the TV and radio stations from Reynosa and Matamoros. They're local stations just like the US stations. As mentioned before, the Fox affiliate here- XHRIO 2- is licensed to Matamoros. This station was at one time a UPN affiliate and before that was the Telemundo affiliate for McAllen and Brownsville. The first Fox affiliate here- XHFOX 17- was also a Mexico station. The Televisa stations XHAB 7 and XERV 9 air alot of commercials for American businesses. They even have a sales office in McAllen. Almost all of the Mexico stations are also available on cable.
And the people in Mexico can also pick up the American stations. My sister went with her friend to eat over there once. On the way they stopped at the friend's dad's workplace and in the lobby the TV was tuned in to "Boy Meet's World" on the ABC affiliate. I don't know how many people in Northern Mexico watch ABC, NBC, and CBS shows in English but I'm pretty sure there are some.