The data came in a csv file which was then converted to an xlsx file in Excel. No mention of original coordinate system, and the fields were just named - "LATITUDE" and "LONGITUDE, respectively.
It doesn't look like Decimal Degrees (DD), Degrees Decimal Minutes (DDM), or Degrees Minutes Seconds (DMS), and I don't think it's any of the single field notations like MGRS.
Data is originally from the Alaska Department of Natural Resources (DNR) provided as a csv.
The problem isn't finding the right coordinate system, but rather the notation used to represent the coordinates. For example, DMS, DD, or DDM.