Alex Tabarrok notes that disproportionate representation of rural areas was instrumental in passing Prohibition:

I’d always understood that prohibition was, in part, an attack by rural WASPs against urban, (often) Catholic, immigrants but I had not realized how much the drys were helped by malapportionment in the state legislatures which gave rural voters greater power than their numbers alone would have suggested.

“Statewide wet majorities were rendered irrelevant by the rotten-borough legislatures.  The very same day the citizens of Missouri rejected a dry amendment to the state constitution by a margin of 47 percent dry to 53 percent wet, they elected a legislature that just two months later would ratify the Eighteenth Amendment by a 75 percent to 25 percent margin. In Ohio, the sacred cradle of the ASL, legislative districting and assiduous politicking put ratification over by a combined legislative vote of 105-42; however, when left to their own devices, Ohio voters rejected the very same measure in a referendum.”

Along with often-abused Senate procedures like holds and filibusters, this phenomenon is one of the hidden structural problems that keep gay marriage illegal and climate change unaddressed.