Lyric discussion by ausGeoff 

I can't be sure that Springsteen is using "the river" as analogous for life in general, OR a vagina as the source of the beginning of life - youth, optimism, hope etc. I tend to the former, as he says repeatedly "we" go down to the river, rather than "I" go down to the river.

As others have said, a river is a lot like life in that it rolls on relentlessly, carrying with it all sorts of positives - irrigation, transport, a food source, and obviously the very basis of life - water.

But... it can flood, or dry up, with devastating consequences - just like life. I'm guessing that Springsteen is just expressing the loss of hope for the future of the boy and Mary's life together, as they've been beset with disaster; he's broke and unemployed, and she's (possibly?) terminated an unwanted and unsupportable teenaged pregnancy.

From an optimistic future, they've fallen permanently on hard times - the river has dried up.

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