The professional writing major is similar to a general writing degree, although likely without the more creative elements available, such as work in poetry or creative writing.
You will also learn to produce different composition formats, such as white papers, instruction manuals, assembly instructions. Arizona State University offers a BS in Technical Communications.
In addition, you may want to consider a combined major in technical writing and another discipline, such as Michigan Tech's BS or BA in Scientific and Technical Communication.
The craft of writing encompasses many disciplines, and there are many related college majors to choose from.
Potential writing majors should keep in mind the conventional advice about selecting a college and program.
You'll learn to manipulate words and syntax in a very thorough and specific way, which will undoubtedly buoy your writing.
Linguistics is one of the more commonly available undergrad programs, but for more specialization, check out Georgia Southern University's BA in Writing and Linguistics.
There is a stand-alone major in publishing offered at many universities, however, these majors seem to be for those interested in working for publishers, and are not aimed specifically at writers.
However, most publishing majors do seem to have a fair amount of editing instruction, so they could prove helpful in launching a freelance writing or freelance editing career.
That constant practice can hone your writing skills, and expose your writing weaknesses.
A requisite editing class was never lost on any freelance writer, either.