Nearly 70 years ago, in 1940, when the US had 100 million people there were less than a million Methodists. Today, when the US has about 300 million people, the Methodists have, well, less than a million communicants.
Well, no. According to the Association of Religion Data Archive, there are over 10 million adherents of the United Methodist Church. Other sources put the number at nearly 20 million adherents.