Prospects as a prospective History Ph.D. in the job market do scare me, and I do wonder whether or not spending the better part of the next decade getting this degree is going to be worth it. Ultimately, given that it is something I (and I assume, you) really enjoy doing, I can't imagine what the alternative would be. There's the option of a professional degree such as law or business, but if the options are diving into the job market now with a B.A. or later with a Ph.D., I'd rather wait. The pay-scale is often higher depending on your degree so even if you do wind up getting a job outside your field, you've benefitted from having been on that track and, who knows, if the prospects get better later on, you'll be more qualified than if you hadn't done it.
Although I do believe that the graduate school you come from makes a difference in terms of the quality of your academic job later on, I also do believe that if you produce academic and scholarly work and make yourself competitive within the field, you'll be fine. My dad used to teach at OSU and my mom got her Ph.D there... she seemed happy with it and it is a respectable place to build up from. I wouldn't worry too much about it, but I would definitely make the best of your time there.