I don't know what year the first spanking party of any kind took place, but they've probably been around for decades (a 1967 issue of Eye has an article on "London's Spanking Parties"). If we confine ourselves to widely-publicized events, however, I think they only go back about 20 years (the first Chicago Crimson Moon party was 1993; I'm not sure what year the first Shadow Lane party was). Like most of the people who got into the party scene during the 90's, I found it unbelievably exciting at first

What happened? For one thing, the women I most enjoyed playing with stopped coming to Crimson Moon for one reason or another, making it difficult to find play-partners. I didn't go to other parties (except the 2001 Shadow Lane party in Palm Springs) because they were all a long way from Chicago. As for that 2001 SL party, I found that most people tended to break up into little private parties in someone's room, leaving little chance to meet people in the party room. To those who say "You've got to network before the party" I find that's easier said than done - and isn't the whole point of a party to function as a mixer anyway? By 2006, I was playing so little at the parties I had to ask myself why I was even bothering any more.
Now it is certainly true that your gender and orientation will affect just how much in demand you will be at a party. If you are female, then regardless of whether you're a Top or a Bottom, you WILL find men eager to play with you. If you are a male Top as I am, it won't be that easy, and if you're a male Bottom you may have one hell of a hard time finding ANY female to Top you. But lack of play-partners isn't the only factor leading to Spanking Party Burn-Out.
We were all so eager back in the 90's, bursting with pent-up spanking desires, and those of us who were not yet middle-aged could dream of finding someone to spend their lives with. But that isn't easy under any circumstances, and what I found was that confining your mate-search to spankos only makes it tougher - after all, you've now eliminated the 99% of the opposite sex that isn't into spanking! Running through dozens or hundreds of spanking partners seemed like kind of a dead-end somehow - we played and played and played, and it wasn't new any more, and their seemed less and less point to it all.

I've attended only two parties in the last three years, and I don't know if I'll ever attend another. There are some who just continue to attend several parties per year and never seem to tire of it, and some who are completely frustrated because they've got zero spanking action and would probably very much like to try a party if they could, but while both groups might find this difficult to understand, Spanking Party Burn-Out is very real.
Although I concentrated on Burn-Out in this post, this topic is for any thoughts you might have about spanking parties - your own experiences, questions about what it's like to go to one, whatever. Don't be shy - post your opinions or questions right here!
Next day update: see separate post below for more information on where the 99% figure came from.