That cost differential goes a long way in explaining why the Loop L has never been replaced with a subway, although proposals to do so date back to at least the 1920's.
And there are still plenty of elevated structures in Da Bronx. Apparently those miles of deck girder viaduct were cheaper to erect and maintain than cut-and-cover tunnels.
Chuck (EX Noo Yawka)
And, 60 years later, its replacement (along with the Second Avenue El) is still under construction.
A note in my local newspaper on today's history says "In 1955, Manhattan's last elevated rail line, the Third Avenue El, ceased operation."
A check of Wiki shows that 1955 was the last year for the 3rd Avenue line in Manhattan, although it continued longer in the Bronx, and on the 9th Avenue line north of 155th Street.
When I was a kid in 1954 our family moved to the NY area (Long Island). In the mid-fifties, I remember them pointing out the "Els" in Manhattan. I believe there are still some elevated sections of the subway system in far northern Manhattan, but officially the "Els" are long gone.
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