The American press have always mostly been blood suckers and bullshit artists...but they weren't sooooo one-sided about it until around 1960. Since then it's been heavily skewed to the Democrats and the left in general.

Much worse in the last 10 years but it kind of ebbs and flows in waves in that same basic leftward direction since the prevalence of TV. Before that you had radio which had pretty strict rules and newspapers which were generally biased but you'd have multiple options in each town so it balanced out somewhat.