Amateur radio enthusiasts have slices of spectrum at every magnitude of spectrum MF and above, but in the US none are below MF.
Why are there no spectrum allocations below 160M?
See the US allocation of frequencies for the source data for some of this.
Right now, the current users of VLF/LF are either maritime mobile, radio navigation, time frequencies, or aeronautical use. There are a few stations that have experimental privileges, as ARRL mentions. The bandwidth for these bands drops dramatically, often only a few kilohertz.
As Wikipedia mentions, the reason why the 2200 band isn't available in the United states is:
On May 14, 2003, however, the FCC declined to grant these privileges citing concerns over potential interference with power line communications (PLC) systems operating unlicensed under Part 15 used by electrical utilities to control the power grid. But the FCC added that amateurs wishing to experiment with 136 kHz communications may apply for a Part 5 Experimental License or operate under Part 15 regulations for this part of the electromagnetic spectrum.
See also the FCC ruling directly, which specifically states:
While we agree that amateur experimentation in the 135.7-137.8 kHz and 160-190 kHz portions of the LF spectrum could serve to increase the pool of individuals having knowledge of LF transmissions, we conclude that such operations would pose the potential for harmful interference to systems protecting and controlling the national power grid.