Soccer is still a long ways behind the "Big 4" in North American sports, but those days may be numbered. According to a recent poll by ESPN, soccer is the second most popular sport among Americans ages 12-24 and the most popular sport among Hispanics. Now, MLS is still less popular than international soccer, but this trend has definitely had the effect of raising all boats. The study says 7.0 percent of all Americans 12+ are "AVID" MLS fans, the highest level the league has ever reached.
MLS has come a long way since 2000 when the league really bottomed out with just 2.8% of Americans were considered AVID MLS fans and had the worst attendance numbers in their history, averaging about 13,700 fans per match. The next year the league folded the Miami Fusion and Tampa Bay Mutiny.
Following a season in which many MLS teams set new attendance standards and the league as a whole obliterated past records for total and average attendance, the upward trend is undeniable.