This might be something of a curve ball but its something I've been thinking about for a while. Years ago i read Ursula LeGuin's classic SF novel The Dispossessed. The premise is that an incipient workers revolution was averted on a fictional planet by encouraging a movement for mass colonization of that planet's very habitable moon. The colonists form a utopian society, develop their own language and culture. LeGuin's novel is far from hard science, it more explores the ambiguities of utopianism and is something of a coming of age story.
Anyway, what would have to happen for something like this to take place in "real life"? I'm think about a time period during the highpoint of the First Industrial Revolution, say from the mid 19th to very early 20th century, involving a successful (at least up to a point) radical socialist colonization of the western US, western Canada, or possibly New Zealand.
While this may sound bizarre at first, there have been parallels in OTL. I'm thinking of the Mormon settlement in Utah, the British colonization of New Zealand by "utopian" factions of the Presbyterian Church and Zionist settlements in Palestine.
Caveats..I'm very much aware that colonization was opposed by Marxists and revolutionary socialists. Eugene Debs proposed a colonization scheme for Western Canada in the very early US Socialist Party more as a political maneuver.I'm also aware of the ambiguities inherent in forming a "settler state", trying to build a utopian society in an area where a population already lives.
Anyway, is it plausible for a radical utopian movement with roots in either utopian socialism or more radical revolutionary socialism, to create their own society, develop their own society with their own language and culture, surviving until today, with a population of at least 5 million?