ConcealedNation.org posted an article that covers every state and whether you have a duty to inform law enforcement if you are carrying a firearm. This article comes after the plight of Brian Fletcher. A NC Tower Climber who was arrested in NJ for possessing a firearm.

Here is a quick summary provided by Concealed Nation. The states are hyperlinked so you can click on them and go to the actual wording of the law and the interpretation by Concealed Nation.

Alabama – If Asked (No known duty to inform law enforcement)
Alaska – Yes (Always)
Arizona – If Asked (If Asked – Yes)
Arkansas – If Asked (Must inform occupant of private home)
California – If Asked (No known duty to inform law enforcement)
Colorado – If Asked (No known duty to inform law enforcement)
Connecticut – If Asked (No known duty to inform law enforcement)
Delaware – If Asked (See *NOTES)
District of Columbia – If Asked (No known duty to inform law enforcement; in flux!)
Florida – If Asked (No known duty to inform law enforcement)
Georgia – If Asked (No known duty to inform law enforcement)
Hawaii – Unknown At This Time (Essentially No-Permit State)
Idaho – If Asked (No known duty to inform law enforcement)
Illinois – If Asked (See Notes* — Thank you, Illinois concealed carriers!)
Indiana – If Asked
Iowa – If Asked (No known duty to inform law enforcement)
Kansas – If Asked (Non-Resident, Residents have constitutional carry)
Kentucky – If Asked (No known duty to inform law enforcement)
Louisiana – If Under The Influence (See Notes)
Maine – No (Permitless Carriers – Yes; See Notes…)
Maryland – If Asked (No known duty to inform law enforcement)
Massachusetts – If Asked (No known duty to inform law enforcement)
Michigan – Yes (Always)
Minnesota – If Asked (No known duty to inform law enforcement)
Mississippi – If Asked (No known duty to inform law enforcement)
Missouri – If Asked (No known duty to inform law enforcement)
Montana – If Asked (No known duty to inform law enforcement)
Nebraska – Yes
Nevada – If Asked (No known duty to inform law enforcement)
New Hampshire – If Asked (No known duty to inform law enforcement)
New Jersey – If Asked (No known duty to inform law enforcement)
New Mexico – If Asked (No known duty to inform law enforcement)
New York – If Asked (see *Notes)
North Carolina – Not Explicitly But Yes (see *Notes)
North Dakota – If Asked (No known duty to inform law enforcement)
Ohio – Yes (Always)
Oklahoma – Yes (Must also inform private property owner)
Oregon – If Asked (No known duty to inform law enforcement)
Pennsylvania – If Asked (No known duty to inform law enforcement)
Rhode Island – Please Do!  If Asked…
South Carolina – Yes
South Dakota – If Asked (No known duty to inform law enforcement)
Tennessee – If Asked (No known duty to inform law enforcement)
Texas – Yes (If asked for ID)
Utah – If Asked (No known duty to inform law enforcement)
Vermont – Constitutional Carry
Virginia – If Asked (No known duty to inform law enforcement)
Washington – If Asked (No known duty to inform law enforcement)
West Virginia – If Asked (No known duty to inform law enforcement)
Wisconsin – If Asked
Wyoming – If Asked (No known duty to inform law enforcement)