Blues have the #5 fan base according to Nielsen study  St. Louis
Blues fans are a passionate bunch. However, many have speculated
that the fan base is dwarfed by those in other cities due to a
variety of factors, including the fact the city of St. Louis is
considered a baseball town.   A report from Nielsen analyzed the
various U.S. sports markets and ranked each team in each sport
in terms of "percent of population that watched, attended, or
listened to the team in the past 12 months." There were other
factors involved (such as competing teams in the same city), but
the entire report requires you to request permission from
Nielsen.   So where did the Blues rank? Surprisingly, they
checked in at the fifth spot on the list.   It's worth noting
that no NHL clubs from Canada were ranked on this list. If they
were, it's safe to say at least a couple teams would be in the
countdown.   It's also important to note that I haven't read the
full report. Feel free to request access to their report if you
want to view it