As of 10/1/2025 the NRCS has uploaded twenty-two (22) county mosaics for 2025 NAIP. 

A map of the available county mosaics is available:
https://ftpgeoinfo.msl.mt.gov/Data/Spatial/MSDI/Imagery/2025_NAIP/UTM_County_Mosaics_MT_NAIP_2025_map_20250826.jpg

The mosaics are now also available to download from the Montana State Library:
https://ftpgeoinfo.msl.mt.gov/Data/Spatial/MSDI/Imagery/2025_NAIP/UTM_County_Mosaics/

Or you can download them directly from the NRCS here:
https://nrcs.app.box.com/v/gateway/folder/338021774329

They are named with the county FIPS code.
A map and a list of the Montana counties and their FIPS code can be found here:
https://msl.mt.gov/GIS/Boundaries

Map (PDF): https://ftpgeoinfo.msl.mt.gov/Documents/Maps/Individual/20190502_808_CountyCensusFIPS.pdf
List (Excel): https://ftpgeoinfo.msl.mt.gov/Documents/MSDI/Boundaries/MontanaCountyList.xlsx