In fact, the Washington caucuses were the largest caucuses in the nation with more attendence than in any other state. This is what it looks like anyway.Well, that's of course true. Raw numbers wise, Washington does have the largest amount of caucus goers. But, because Washington is the largest state to still use the caucus system, I should hope we had the most.
If you look at the number of caucus attendees as a percentage of the voting eligible population (according to here) and Kerry votes in 2004, Washington isn't so great. Here's my spreadsheet.
VEP percentage is 5.42% (4th out of 11 caucus states so far) and Kerry vote percentage is 16.55% (4th of 11 again).
Guess which state had the most Democrats attending caucuses as a percentage of their population that voted for Kerry in 2004. New Mexico with a whopping 41 percent!