By membership I do -not- mean registration to vote for a party; meaningful participation in the political organization, from local office, all the way to national committee level, and of course actual elected and political appointments.

I don't have the numbers but wouldn't surprise me if it turned out to be an even smaller fraction of total population than the Chinese single party.

Roughly take US as 1/3 of population of China, and then test expectation that 91/3 => ~30,000,000 politically active members of political organizations in US. Again, I don't have the numbers, but I would be shocked if actual party members in US even reached the 1 million mark, much less 30 million people. For fairness, let's throw in 18 million Americans that belong to unions. Let's make it 20 millions in total. That's still less than the required 30 million politically organized Americans to be at par with CCP.

[but p.s. /g! If we throw in the 18 million American millionaires, then we have a system that is a bit more representative than the CCP]