Yes, Jack, the current Cascade Tunnel had overhead wire in it ,until the GN pulled the plug in 1956. The problem is, that 1956 - era overhead clearances will not clear modern double stacks or super - max auto racks. In the 1960's, Milwaukee had to raise the wire &/or undercut the ties in all their tunnels on Lines West, to clear auto racks. Also recall that BN had to notch the ceiling to clear today's tallest double stacks( 2 ea - 9' containers in the same well ). I'm sure the engineering dept. would want a safety margin in overhead wire, just to avoid the problems Milwaukee had even after increasing clearances. Seems that raised upper deck car radio antennas would come in contact with the 3000 volt overhead, resulting in a pile of ashes where the radio used to be !!!
Regarding electric freight operations on the Northeast Corridor, such use was ended by Conrail in the early 1980's. In fact, very little freight uses the NEC at all nowadays, due to high fees & high usage by Amtrak.