5.64 Only classes A1A or F1B, A2C, A3C, F1C or F3C emissions are authorized for stations of the fixed service in the bands allocated to this service between 90 kHz and 160 kHz (148.5 kHz in Region 1) and for stations of the maritime mobile service in the bands allocated to this service between 110 kHz and 160 kHz (148.5 kHz in Region 1). Exceptionally, class J2B or J7B emissions are also authorized in the bands between 110 kHz and 160 kHz (148.5 kHz in Region 1) for stations of the maritime mobile service.
5.68 Alternative allocation: in Congo (Rep. of the), the Dem. Rep. of the Congo and South Africa, the frequency band 160-200 kHz is allocated to the fixed service on a primary basis. (WRC 15)
5.69 Additional allocation: in Somalia, the band 200-255 kHz is also allocated to the aeronautical radionavigation service on a primary basis.
5.70 Alternative allocation: in Angola, Botswana, Burundi, the Central African Rep., Congo (Rep. of the), Eswatini, Ethiopia, Kenya, Lesotho, Madagascar, Malawi, Mozambique, Namibia, Nigeria, Oman, the Dem. Rep. of the Congo, South Africa, Tanzania, Chad, Zambia and Zimbabwe, the frequency band 200-283.5 kHz is allocated to the aeronautical radionavigation service on a primary basis. (WRC 19)
US2 In the band 9-490 kHz, electric utilities operate Power Line Carrier (PLC) systems on power transmission lines for communications important to the reliability and security of electric service to the public. These PLC systems operate under the provisions of 47 CFR part 15, or Chapter 8 of the NTIA Manual, on an unprotected and non-interference basis with respect to authorized radio users. Notification of intent to place new or revised radio frequency assignments or PLC frequency uses in the band 9-490 kHz is to be made in accordance with the Rules and Regulations of the FCC and NTIA, and users are urged to minimize potential interference to the extent practicable. This footnote does not provide any allocation status to PLC radio frequency uses.

Wiki entries

Ground Wave Emergency Network (GWEN)

Historical Use 150–175 kHz Ground Wave Emergency Network (GWEN)

The Ground Wave Emergency Network (GWEN) was a radio communications system designed to relay emergency messages between strategic military areas in the continental United States. The system was claimed to be immune to the effects of high-altitude electromagnetic pulse (HEMP) energy surges caused by nuclear detonations in the ionosphere, which would disrupt the nation's electric power line transmission capability, cripple electronic devices, and adversely affect skywave communications networks based on conventional electronics. A failure of such equipment would prevent timely communications among top military and civilian leaders and strategic Air Force locations and prevent U.S. assessment and retaliation during an attack.

The GWEN system was a network of relay nodes, receive-only stations, and input/output stations. Each relay node consisted of a guyed radio tower facility similar to those used by commercial AM broadcast transmitters. Relay nodes provided essential connections with adjacent nodes in the network. Each GWEN station operated intermittently in the LF radio band at 150-175 kHz. The peak broadcast power for each GWEN tower was between 2,000 and 3,000 watts, depending on local soil conditions.

After the end of the Cold War, and because of lingering protests over radio frequency interference and adverse health effects (including claims that GWEN could be used for "mind control"), the network was defunded in 1994.

[Note: The GWEN frequency table in the referenced Wikipedia article appears to be incorrect, since it lists frequencies in the 285-325 kHz band, which is not the band used by GWEN.]