When you ask using the word, "Greatest" American spectator sport, it complicates the answer a little bit, I believe. Because we must ask, what makes a sport "The Greatest Spectator" sport? Or what will we base that conclusion upon?
If we determine or define the "greatest" American spectator sport by the number of spectators annually then I believe we must conclude the league, "Major League Baseball" according to sources, again based upon the number of people attending the sporting events, MLB.
Now of course, if we say Major League Baseball is the "Greatest Spectator" sport in America, we might have various subjective opinions regarding that statement. In fact, based upon your question, it might be unclear regarding whether or not you are speaking of only professional spectator sports or in general, of all American spectator sports?
To know the exactness of your question would determine how exact the answer might be. In this case, I will assume you are inquiring of professional sports. Of course, to include college and even high school and grammar school etc. might change the answer, maybe.
What is the second most attended sport in America? I was shocked to read, "Horseracing" as the second most attended sport in America today. But then again, perhaps I should not be surprised considering baseball and horseracing were the two big sports back in the day. And today, gambling is what pumps up horseracing today.
Written by Pall Stanley (unedited)
it IS the GREATEST SPORT !
FOOTBALL
Its not.
No.
cricket, by far!
hockey is a fun sport in my option! but not all may like it!!
A performer loses his ego while performing a ritual. A spectator witnesses transcendence demonstrated.
There are cheerleaders in the sport of American Football.
baseball
Lacrosse (oldest American Sport), Hockey (not really American, though)
UFC.
It is a matter of personal opinion.