USA - Quick summary of knife laws

Explaination

• Summary:

Basically, I want to answer the question "I'm flying to state X tomorrow, so which knife can I take?"
• Max length:

Size limit, measured the most unpleasant way possible. Some may permit longer in certain cases, but I won't suggest anything longer if it's in a gray area.
• Specifically illegal:

Specific styles which are explicitly forbidden.
Switchblade= Push a button/lever, it does the rest.
Gravity knives = Opened by gravity or centrifigual force. Butterfly knives (balisongs) included.
• Relevant laws:

A quick pointer to roughly where the relevant laws are (ex. Penal Code 642)
• Quirks:

Dark humor points (ex: a 1" lockback in a pocket is illegal, but a 15" Bowie swinging free is ok)
• Local restrictions:

City/county restrictions.

US Knife Law Summary

• Ballistic knives (automatic blade throwers) are prohibited.
• Switchbladesmay not be transported/mailed across state lines unlessthe recipient intends to use it for military use.
• Possessing a knife in a federal facility is prohibited unless it is a pocket knife with blade under 2.5".

State Knife Law Summaries

• Summary: Generally clear. Illegal to carry "deadly weapon, (except a pocket knife) concealed."
• Max length: None apparent.
• Relevant laws: ARS book

• Summary: Anything capable of ready use as a stabbing weapon is illegal. All concealed knives are a felony (except non locking folders).
• Max length: chaotic
• Specifically illegal: Switchblades, gravity knives, exotic conceal methods (pen, lipstick, whatever)
• Relevant laws: PC 653K, PC 12020(24), California Laws, Commentary (apparently removed - someone know where?)
• Note that interpretations by cops and judges are wildly varied. Police have actually told law-abiding citizens to break the concealment laws, and a judge has deemed a blunt-point knife (Spyderco Mariner) a stabbing weapon.
• Quirks: Pens may be illegal (potential stabbing weapon).
• Local restrictions:
• Los Angeles
• Three inch limit for open carry without a good explanation.

• Summary: Sounds normal.
• Max length: Cutting edge under 4 inches
• Switchblades: Are legal to carry with a Dangerous Weapons Permit (DWP) only. Good luck trying to find a police station that has an application.
• Gravity knives: Same
• Relevant laws:
• Local restrictions: Some police chiefs don't want to give out DWP's

• Summary: A "common pocketknife" is OK. All "concealed weapons" (knives included) require a license.
• Max length: None apparent.
• Relevant laws: Chapter 790

• Local restrictions:
• Atlanta: A blade over 3" that LOCKS is illegal.

• Summary: Generally OK.
• Max length: None apparent.
• Specifically illegal: automatics & throwing stars.
• Relevant laws: Statutes mentioning "knife"

• Summary: OK for "normal" knives. Don't try to conceal any bowie, dirk, switchblade or butcher knife.
• Max length: None apparent.
• Specifically illegal: none apparent.
• Relevant laws: 97-37-*
• Quirks: Threatening actions with a knife in the presence of less than three people may be acceptable.

• Summary: any folder 4" or less is OK.
• Max length: 4"
• Relevant laws: State Laws (search for "knife")

• Summary: "Penknives" are OK. Anything else is borderline illegal and may require a concealed weapon permit.
• Max length: None apparent.
• Relevant laws: MD Statues Crimes and Punishments § 36, § 36A-O
• Quirks: You may carry a "weapon as a reasonable precaution against apprehended danger", but it's up to a tribunal to decide the reasonableness/appropriateness of posession.
• Local restrictions:
• Cecil, Anne Arundel, Talbot, Harford, Caroline, Prince George's, Montgomery, St. Mary's, Washington, Worcester, Kent, and Baltimore Counties have special prohibitions regarding children under 18 carrying knives. See § 36(a)(3).

• Summary: Nothing over 3.5"
• Max length: 3.5"
• A longer blade maybe legal, but it's subject post-fact to a judge's decision.
• Relevant laws: Statutes mentioning "knife"
• Statutes may refer only to concealed knives.
• Quirks:
• A "knife" is defined as having a blade over 3.5". A pocketknife under 3.5" is not a knife.
• Local restrictions:
• Linconln
• Switchblades are illegal.

• Summary: General folders OK. Single-edged fixed blades may be.
• Max length: Under 18 may not possess knife with 5" or longer blade, or 10" or longer overall. No other apparent limitation.
• Specifically illegal: gravity knife, switchblade knife, dagger, dirk, stiletto, or ballistic knife "without any explainable lawful purpose" (i.e. an ill-defined exemption). Manufacturers and sellers are not exempt.
• Relevant laws: 2C:39-3.e 2C:39-9.d 2C:39-9.1 (Statutes, search for "knife" or "knives")

• Summary: If it looks like a weapon, it's illegal.
• Max length: 6" (?)
• Specifically illegal: Switchblades and gravity knives unless hunting or fishing with permit
• Relevant laws: Penal law
• Local restrictions:
• New York City
• Must be under 4"

• Summary: Generally OK.
• Max length: None apparent.
• Specifically illegal: switchblades, belt-buckle knives
• Relevant laws: NRS 202

• Specifically illegal: switchblade, springblade knife, gravity (butterfly) knife, or similar weapon;
• Relevant laws: Search Statutes for "knife"

• Summary: 3" or less OK. Don't posess anything "designed to cut and stab another".
• Max length: 3" measured from where the handle ends, not where the sharpened edge begins.
• Specifically illegal:
• Posession of a dagger, dirk, stiletto, sword-in-cane, bowie knife, or other similar weapon designed to cut and stab another.
• Concealed carry upon one's person of the above-mentioned instruments or weapons, or any razor, or knife of any description having a blade of more than 3".
• Relevant laws: Title 11 Criminal Offenses § 11-47-42
• Quirks: Children under 18 may purchase the above weapons with written parental permission.

• Summary: Folders under 4" are OK.
• Max length: 4"
• Specifically illegal: Switchblades, gravity knives (probably)
• Quirks: Fixed blades are probablya no-no.

• Summary: Folders under 5.5" OK.
• Max length: 5.5"
• Specifically illegal: Switchblade, throwing knives, daggers (in general), bowie knives, swords and spears.
• Relevant laws: Penal Code 46
• Quirks: The one state people associate with Bowie knives explicitly forbids them.

• Summary: Don't conceal a dirk or bowie knife. Don't take a dangerous weapon (esp. bowie knife or dagger) to church.
• Max length: None apparent.
• Specifically illegal: Switchblades.
• Relevant laws: 18.2-308, search statutes for knife or knives.
• Quirks: 3.1-370: your knife must be cleaned daily.

• Summary: Anything over 3" is in a gray area.
• Max length: 3"
• Specifically illegal: switchblade, springblade knife, gravity (butterfly) knife, concealed dagger/dirk
• Relevant laws: Statutes mentioning "knife"

• Relevant laws: 134.71 (1)(a)9, 134.71 (1)(g)1, 134.71 (1)(h)1  (relating to pawn brokers), 941.24 (switchblades)

• Summary: Careful; the country is getting antsy about weapons.
• Specifically illegal: a knife that has a blade that opens automatically by gravity or centrifugal force or by hand pressure applied to a button, spring or other device in or attached to the handle of the knife.
• Relevant laws: Annual Statutes Of Canada, 1995 Chapter 39 (Bill C-68)