Yeah, if there was truly a comprehensive societal collapse there's no way the lower 48 could support the 300+ million folks already here. It takes advanced agricultural tech to produce that much food. If things really go to heck in a handbasket we can safely assume no fuel to run combines or to plant, no way to get the harvest to market if there was a harvest, etc.
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“I'd rather have questions that cannot be answered than answers that can't be questioned.” —Richard Feynman