MYSTERY FREQUENCY 172.4000 MHz

Reports of activity on172.4000 MHz, N088 in the Long Island, NY region. No other information was provided. 

For what it's worth, the frequency of 172.4000 MHz is assigned to mostly US Department of Agriculture and Department of the Interior agencies;
Animal/Plant Health Inspection Service
US Forest Service,
Bureau of Reclamation
International Boundary and Water Commission,
National Park Service
Soil Conservation Service

There are a few allocations to the US Army in New Mexico.

I have logged the N088 NAC a few times in Pennsylvania, and around the DC area out by Dulles airport, but not on this frequency.

MYSTERY FREQUENCY - 166.1125 MHz

 During a recent POTUS motorcade in Delaware, a listener caught a Close-Call hit on 166.1125 MHz, N001. This has not been noted previously as a Secret Service or White House Communications Agency frequency in the past. 

This frequency has no previous records to any federal agency in the NTIA data I have seen, so this may be a new assignment. As to who or what it is used for, remains to be seen.