An excellent question that deserves some serious treatment IMO. To begin with, I don't know of a major metro area that still has a "conservative" paper. If memory serves(and it may not), up until the late 70's - early 80's, most major metro areas still had at least two competing dailies; each with their own "slant". The conservative leaning dailies still around then either began to fail or were acquired(not sure which) by and consolidated into the liberal rag.
Now, how and why this came about I haven't a clue. There are any number of reasons, or combination or reasons, why this could have happened; none of which I've ever seen discussed in any serious format. The reasons can run from mundane to tinfoil hat stuff, but the bottom line is the leftist media apparently outperformed(by hook or crook) conservative media. It might be instructive to get to the bottom of it, eh?
FGS
Yes, very instructive. Things have changed dramatically in the last 10 years. Conservative radio, led by Rush took over talk radio. Fox News has CNN possibly on the verge of bankruptcy. This could be one of the most interesting plays in media history.