The United States Secret Service is best known for their mission of protecting the leaders of the most powerful nation on Earth. When they aren't tasked to protecting the physical well being of the leaders of state, they are busy behind the scenes defending the economic machine.

US Secret Service Mission Statement

The United States Secret Service is mandated by statute and executive order to carry out two significant missions: protection and criminal investigations. The Secret Service protects the President and Vice President, their families, heads of state, and other designated individuals; investigates threats against these protectees; protects the White House, Vice President’s Residence, Foreign Missions, and other buildings within Washington, D.C.; and plans and implements security designs for designated National Special Security Events. The Secret Service also investigates violations of laws relating to counterfeiting of obligations and securities of the United States; financial crimes that include, but are not limited to, access device fraud, financial institution fraud, identity theft, computer fraud; and computer-based attacks on our nation’s financial, banking, and telecommunications infrastructure.

Presidential Visit Frequencies
Protecting the President Of The United States (POTUS) is the what the Secret Service is best known for. With that in mind, this list of commonly used frequencies has been placed at the top of this page. The US Secret Service Presidential Protection Division (PPD), the folks who are paid to take a bullet, uses the "SNOW" channels when the President is in town.
166.5125 SIERRA (Simplex)  (P25 Digital Encrypted)
166.7000 NOVEMBER White House Staff (Encrypted)
164.8875 OSCAR Presidential Protection (Primary) (P25 Digital)
167.0250 WHISKEY Paging
The local US Secret Service Field Offices use the following frequencies.
165.7875 BAKER (P25 Digital)
165.3750 CHARLIE Command Post  (P25 Digital Encrypted)
164.6500 TANGO (P25 Digital Encrypted)
165.2125 MIKE Motorcade (P25 Digital Encrypted)
Local law enforcement use the following frequencies.
406.8000 103.5 NALEMARS UHF
155.4750 100.0 NALEMARS VHF
Even though the US Secret Service doesn't cut the pay checks for the folks protecting the President from high above, the following frequencies have been included to make this list complete. The US Air Force and Air National Guard provide Combat Air Patrol (CAP) for the President where ever he goes. Notice To Airmen (NOTAM) alerts are published, giving pilots flying in the vicinity of the President detailed instructions on the areas to avoid. The following frequencies can be quite exciting to monitor when a pilot, who forgot to check the NOTAMs before flight, ventures into the restricted air space. You will hear on these frequencies armed fighter jets refueling with air borne tankers, general chit chat between the pilots, conversations with NORAD and interceptions of aircraft intruding on the restricted air space.
271.0000 BLUE 15 (Talking with tankers and NORAD)
138.2250 VICTOR 12 (AM mode) (Air to air chit chat conversations)
121.5000 Guard VHF (Used to contact pilots intruding into restrict air space)
148.1250 NORAD Nationwide (AM mode)

White House Communications Agency
Channel	Description	Frequency
Green	Training division	415.7500	407.8750
Black	Training division	415.1000	418.3250
Blue	Training/protective support divisions	414.8000
Violet	Training division	415.8750
Gray	Protective support division	415.8000
Gold	Communications division	415.6750	419.0750
Black	Executive protection division	415.6750
Orange	Executive protection division	414.9500
Tan	Foreign Mission divisions	414.8500
Brown	Uniformed division	414.8500	418.8000
Red	Foreign Mission/Uniformed divisions	415.9750	419.7250
Silver	Foreign Mission/Uniformed divisions	415.6500	419.1000
Gray	Uniformed division	418.3500	407.7500
Orange	Uniformed division	418.7750	414.9500
Yellow	Uniformed/Technical security divisions	414.6750	418.1500
Green	Technical security division	419.7250

Technical security division (special use)
Description	Frequency
RF Alarm 1	408.0000
RF Alarm 2	411.0000
Tracker 1	408.5000
Tracker 2	408.9750
Wireless body microphone	406.2625
Wireless body microphone	407.8250
Wireless body microphone	407.8750
Wireless body microphone	407.9750

Presidential Nighthawk Aircraft Fleet (HMX)
Description	Frequency
Helicopter ops/transport (primary)	46.7500
Helicopter ops (secondary)	46.7000
Helicopter ops (alternate)	46.8000
VIP transport net	34.3500
Transport	375.0000
Command post	142.7500
Squadron common	265.8000
Limousines (local-DC)(duplex)	407.8500
Limousines (local-DC)(duplex)	408.4500

AF1/2 Orderwire UHF (wideband FM) (sidebands used for phone patches)
Uplink	Downlink	Description
382.3500	326.0000	F1
305.5500	246.9500
336.8000	344.0000
322.7500	366.0000
397.0500	390.0000
407.4750	415.8000	Nationwide-2 phone patch