See the WIKI for more information on unidentified frequency uses and unit numbers. 

Frequencies

Miscellaneous

Miscellaneous

Thomas F. Eagleton United States Courthouse
No actual frequencies confirmed. 
 (Maintenance provided by General Services Administration (GSA)

Federal Reserve Bank of St Louis
Gateway Arch National Historic Site/Gateway Arch National Park
United States Postal Service 
US Department of Justice - 25 Cities Interoperability Project
 Customs and Border Protection / TSA
 DEA - Drug Enforcement Agency (St Louis)
 FBI - Federal Bureau of Investigations
 Federal Protective Services - Region 6
 National Geospatial-Intelligence Agency
 United States Secret Service

See St Louis City for these agencies 

Federal Aviation Administration

See Lambert-St Louis Airport for more info

Missouri Statewide Wireless Interoperable Network (MOSWIN)
Project 25 Phase II
Airport Operations and more
Gateway Arch National Historic Site

Military

Coast Guard
Mississippi River - Commercial river traffic uses Marine Ch 13, recreational uses Ch 9 and Ch 16 is a hailing channel. 
For more, see Maritime Database and American Boating Association.   US Army Corp of Engineers control the locks and dams
Jefferson Barracks National Cemetery
FrequencyLicenseTypeToneAlpha TagDescriptionModeTag
166.7125 BM 91.5 PL JBNC Ops 1 Operations / Military Honor Guard FMN Military
172.6875 BM 91.5 PL JBNC Maintenance Maintenance FMN Military
St. Louis VA Medical Center - Jefferson Barracks Division

Provides psychiatric treatment, spinal cord injury treatment, a nursing home care unit, geriatric health care, rehabilitation services, and a rehabilitation domiciliary program for homeless veterans.

FrequencyLicenseTypeToneAlpha TagDescriptionModeTag
408.2375 RM 293 NAC JC Security A1 Security [TG 1] (simulcast w/ 408.0 at JB) P25 Security
St. Louis VA Medical Center - John Cochran Division

Located in St Louis City