I got an email from a harness watcher (thanks Beav!) noting a blog post from Robert Smith. He looked at one single day in 1986 at various tracks, detailing both attendance and handle. This was in the dead of winter, to boot.
Greenwood Raceway : Attendance 10.179, Handle $1,931,591
Orangeville (now closed), a whopping handle of $283,334. This with average purses of about $600.
Cloverdale in BC, over $500,000.
Blue Bonnets in Montreal, almost $1M.
All in all, for just that day, with other tracks dark as well, the handle was about $5M. Attendance was over 30,000.
In today's dollars, that puts Greenwood's handle at $4.1M, overall harness handle for the day at over $10M.
It's a different world today. There are so many other options for our time, our gambling dollars and our entertainment dollars. I can't help but think, however, if you had a crystal ball and said "in 20 years we'll be able to bet at home, bet any track we want, at any hour of the day, handles will explode", I don't think too many would disagree with you.
That didn't happen, of course, for the most part. I think one of the major reasons is the fact we increased frequency of potential bets, increased the number of bets (most of them hard to hit), and did not decrease takeout rates to ensure people stayed in play. Losing money more quickly, is an easy way for people to leave you forever.