What inherent physical limitation of Direct Current (DC) made widespread, long-distance electrification prohibitively costly?

Answer

The inability to easily change its voltage level.

DC power could not be easily transformed to high voltages, meaning that to minimize resistive energy loss over distance, extremely thick and expensive copper conductors were required, necessitating a new power plant approximately every square mile.

What inherent physical limitation of Direct Current (DC) made widespread, long-distance electrification prohibitively costly?
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