Last week, President Obama signed a bill which, besides changing credit card laws, says that in National Parks and National Wildlife Refuges, the laws about gun carrying will be the same as in the host state. So in Colorado, for example, you will be allowed to carry a concealed handgun in Rocky Mountain National Park, if you have a state-issued concealed carry permit. In Vermont’s Marsh-Billings-Rockefeller National Historical Park, you can carry at will, since no permit is required for carry in the rest of Vermont. In New Jersey’ Gateway National Recreation Area, you will need a permit, and since almost no-one in New Jersey except retired police is ever granted a permit, almost no-one will be able to carry there.

The law goes into effect nine months hence, as do the changes in credit card laws.

I was one of seven authors whom the New York Times invited to contribute a short essay on the new law, for the Times’ on-line opinion feature, Room for Debate. All seven essays, from diverse pro/con viewpoints, were pretty good, I thought. The comments from readers, however, were voluminous but often very weak. Many of them consisted of left-over talking points from the gun control debate circa 1971, with assertions that no serious scholar of the gun issue believes. For example, many commenters claimed that it is impossible to use a gun in self-defense, because the attacker (whether a human or an animal) will have the element of surprise, that ordinary people are not competent to use guns for protection, and so on. Yet even the strongest scholarly advocates of gun control acknowledge that there are about a hundred thousand defensive gun uses annually, according to the National Crime Victimization Survey, which is conducted by the Census Bureau and the United State Department of Justice. (Other scholars argue for higher figures, but the key point is that no informed scholar claims that successful defensive use is rare or non-existent.)

Surprisingly, some of the commenters showed signs of mental illness. One commenter wrote that if he saw someone in a National Park with a gun, he would report the person for making criminal threats. (“Well, watch out, gunnut gunwack gunsels. If I see your gun while I am visiting the parks, I will file a complaint accusing you of threatening me.”)

Now perhaps that commenter himself is just an ordinary criminal, and for many years has been breaking the law by making false accusations against innocent people. On the other hand, the commenter might not have been intending to make a knowingly false report, but instead to have been accurately predicted what he, with complete sincerity, would do. A person’s belief, without a sufficient basis, that other people are committing crimes against him, is a symptom of Paranoid Personality Disorder.

The more common form of apparent mental illness among some commenters was Hoplophobia, which is described in the book Contemporary Diagnosis and Management of Anxiety Disorders. A word of explanation: having a strong dislike or hatred of something is not, in itself, an indication of mental illness. For example, a person hates frogs, considers them disgusting, tries to avoid looking at frogs or touching them, and writes letters to the editor urging that all frogs be exterminated. This is not per se a sign of mental illness. Poor judgment, perhaps, but not a mental disorder.

So the vast majority of people who hate frogs, snakes, spiders, dogs, cats, guns, animals, George Bush, or anything else are not mentally ill.

Something becomes a Specific Phobia, clinically speaking, when it significantly interferes with ordinary life activities. For example, “I turned down a job offer as a ticket-taker at the Natural History Museum, because I am afraid if I might see a child carrying a plush frog toy that was purchased in the museum gift shop.” Or, “I refuse to visit my son who is a chef in a French restaurant, because I know that he has handled frog legs, and I terrified that he might shake my hand.”

Among the New York Times commenters, there were plenty of gun haters, the large majority of whom exhibited no sign of mental illness. Yet several of them wrote that they often visit national parks, enjoyed the visits, but now, because of the new federal law, they would not set foot in a National Park.

Now, as my Times essay had explained, and other commenters had reiterated, the new federal law simply means that the rule inside federal parks will be the same as in the host state. So the odds of running into a person legally carrying a firearm at, say, the Johnstown Flood National Memorial in Pennsylvania would be pretty close to the odds running into a legally armed person while walking down the streets of Johnstown, Pennsylvania.

In other words, someone who avoids National Parks because of the new law is saying that he is afraid of being in place where most of the adult population has the legal right to carry a firearm, after licensing, a background check, and safety training. Meaning, of course, 40 of our 50 states.

Having so much hatred, or fear, of guns that you can’t handle the ordinary, daily conditions of 4/5 of the American states would imply a rather significant interference with ordinary activities. That is, a phobia. The specific name for this phobia is “Hoplophobia.” Although Hoplophobia would be a good name for fear of hopping animals such as frogs and kangaroos, the word’s root is “hoplon”—from an ancient Greek shield that could be used offensively or defensively.

A caveat on the diagnosis: The American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders includes, as part of the diagnosis for a phobia, that “The person recognizes that the fear is excessive or unreasonable. Note: In children, this feature may be absent.” That condition is not met by the New York Times commenters, who appear to see themselves as eminently reasonable, and to consider anyone who would carry a firearm for protection as self-evidently crazy and dangerous. I don’t think that the diagnosis of a phobia should require insight on the part of the phobic. If a person won’t go to public places because he is afraid of balloons, then he would have a phobia, even if he considered himself eminently rational, and could recite statistics about all the people who have been seriously injured by balloons. (As was one of my relatives, when a Mylar balloon in a department store popped, and left her blind in one eye.)

Generally speaking, a mentally ill person has a better chance of being cured if he wants to be cured, and so the first step towards mental health is recognizing that one is mentally ill. So in the interest of perhaps encouraging some Hoplophobes to admit that they have a problem, here is a travel guide to the United States, based on the presumption that a person refuses to go any place where most adults can lawfully carry firearms for protection.

For convenience’s sake, let’s presume that the victim of Hoplophobia lives in Manhattan. Of course most people in Manhattan, including most Manhattanites who hate guns, are not Hoplophobes. But the island is a place to which Hoplophobes often migrate, perhaps as a form of self-treatment, trying to place themselves in a place where their phobia is less likely be triggered.

So starting in Manhattan, you can enjoy the entire Empire State, a large and interesting place. If you feel a desire to leave New York, be extremely careful about heading east. Going into Connecticut will immediately put you in a place where the government routinely issues carry permits to law-abiding, trained adults. In other words, Connecticut is just as dangerous as a National Park.

Vermont is even worse, with no permits even required for carrying concealed handguns. And everyone knows how dangerous Vermont is. New Hampshire and Maine are similar to Connecticut, and must be avoided.

Massachusetts is safe, as long as you cross directly into the state, without going through Connecticut. Rhode Island is good too, providing that you approach it via Massachusetts, or take a ferry from eastern Long Island. A trip through Connecticut would obviously be too risky.

New Jersey is the Hoplophobe’s Garden State. Its licensing practices are much more severe than New York City’s. In New Jersey, not even diamond merchants or celebrities can get carry permits.

From New Jersey, you must go south to Delaware. Do not even think of crossing into Pennsylvania. It is a Shall Issue state for carry licenses, similar to Maine or New Hampshire.

Maryland is also safe, and from there you can go to the District of Columbia, whose very strict gun laws have made it notoriously safe.

If you want to fly to D.C., take a plane to the Baltimore airport, and then rent a car or take a bus. Do not fly to either of the D.C. airports. They are both located in Virginia, and the danger that you could be shot by a gun-crazy Virginian while traveling through Virginia into D.C. is nearly as high as the odds that you will get shot by a gun nut while in a National Park. Stay away from Arlington National Cemetery; it is in Virginia, and the people buried there were gun users.

Needless to say, the entire Southeast is off limits. So is almost everything from Pennsylvania west. It is OK to fly to Illinois, and enjoy that state, since it does not even have procedures for issuing carry permits. The South Side of Chicago is an especially safe place to go, thanks to the handgun ban in the city.

Like Illinois, Wisconsin has no provision for handgun carry licenses, and so was safe until 2005, when the state Supreme Court ruled that people had a constitutional right to keep and carry guns in their place of business. After that, you could still go to Wisconsin, as long as you never entered a place of business. But now, the state Attorney General has advised that people have a right to open carry without a permit, and thus the Badger State is far too dangerous to contemplate a visit.

So is all the rest of the Midwest. So are all the Rocky Mountain states. So is the entire Southwest.

The Pacific Coast is mixed. Washington and Oregon are Shall Issue states. Alaska allows carry without a permit, and besides that, the mere thought of Sarah Palin can trigger anxiety attacks in Hoplophobes.

California is safe, except for some of the rural counties, where sheriffs issue permits to law-abiding citizens. Permits are close to non-existent in Los Angeles, making South Central L.A. an especially safe area for the Hoplophobe.

Permits are also hard to get in Hawaii. So you can visit Haleakala National Park without worrying that someone on the trail up the volcano may have a gun.

In addition, New York’s airports are gateways to the world, and you can travel to many global locations which are even stricter than New York City in their restrictions on gun ownership. You may find Cuba, Darfur, and North Korea to be especially pleasant places.

David B. Kopel is Research Director of the Independence Institute, in Golden, Colorado.