Commentary in these playoffs has already mentioned many times that Milwaukee is a very small market. It's the smallest in baseball in fact. Seeing as how this is the Brewers first appearance in an LCS since 1982 it seemed possible that this was the smallest market for combined LCS ever?
I decided to dig into a bit as I ran an experiment. It required spurts of activity followed by waiting so it's good time for me to do online research, and occasionally it doesn't have to be work related.
The idea that Milwaukee is the smallest market is based on their Metropolitan Statistical Area (MSA). It works as a general measure of the population of a city area as opposed to the population of the city itself.
A few notes: I limited my analysis to the Wild Card Era because I didn't want to spend an entire week on this and I answered my original question pretty quickly. I used census data from 2000 as an approximation for 1995-2011. While there were some significant changes in populations from 2000-2010 in some markets (i.e. +23% for Dallas-Fort Worth) the lack of yearly data rendered completely accurate analysis impossible regardless of method. You'll notice some years with only three markets. Those are years that two teams that share an MSA both made it to their LCS and it doesn't make sense to count both populations.
So you don't have to go back that far to find a year with a smaller total market.
1995 (first WC year and smallest market)
All three years are lower than the markets for New York (21,195,865) and Los Angeles (16,373,645) alone.
There are some obvious problems with this analysis. The big one is that the MSA is not actually the market for many teams. For some (Baltimore and Washington) their MSA includes another market meaning that the MLB doesn't actually count the entire MSA. There are others (Boston) whose market greatly exceeds their MSA. Still, it was interesting looking into how little my home town, that used to feel so big, really was.