There's at least one other US Navy VLF station as well in Cutler Maine. A few countries have lower frequency ELF transmitters, but the US abandoned its facility.
The VLF land stations are on 24.8 kHz, which is 7.4miles wavelength. The two mile antenna is probably a 1/4 wave dipole.
The sub comms are at 25 kHz, which is 3000m at 1/4 wavelength. So 2 miles makes sense for a 1/4 wave monopole with the Earth as a counterpoise.