Rust Pipeline

There is no “iron pipeline” of guns trafficked from low gun control states to high ones.

There is a rust pipeline of legally migrating guns mainly between neighboring states.


  • Most crime guns are retailed in the state where they were recovered, including in high gun control states.
  • Most intrastate guns come from neighboring states, including other high gun control states.
  • Most guns legally follow owners when they move between states, which frequently are neighboring states.
  • Approximately 6,000,000 guns at minimum move legally between states each, and of these, 433,000 move between neighboring states

Crime guns are largely local

Percent intrastate traced guns 2019One reality is that most crime guns are retailed in the same state where they were recovered. Across all states, 68% of traced guns were retailed in the same state where they were recovered.

But there are significant variations. Due to decades of restrictions, Washington, DC (not a state, but worth including since it has the highest gun homicide rates in the nation) had only 5% of its traced guns originating there. Little wonder, since for a long time there were no DC gun stores per se. The next lowest is 20% (New Jersey, also highly restrictive) and the highest is 85% (Texas).

This is where things get odd and where politicians launch irrational agitprop. And it gets odd on two vectors: where crime guns come from and how long it takes for those guns to be used in crime.

The short story is that it takes a very long time for a retailed gun to be used in a crime, regardless of whether it was retailed in or outside of a state. If “iron pipelines” existed, you would see a very short interval (“time to crime,” or TTC) and it would be consistent among states with strict gun retailing laws.

Neither is true.

Percent Traced Guns that Retailed in Recovery State 2019

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Weapons trafficking - 2019 BATF

Nationally, only six of the 50 states and DC have more crime guns being imported than are retailed within the state (herein we’ll include DC in the mix).

The claim proffered by politicians and other disreputable types is that “iron pipelines” are trafficking networks actively bringing guns from states with fewer gun laws to states with strict gun laws.

That claim fails on two basic points:

RETAIL: Federal law requires guns to be retailed only to residents of the state. A person from New Jersey cannot drive to Georgia and buy a gun at retail. They might buy such on the black market, but “strict gun laws” are almost universally about retailing of guns. So, gun running from retail to street crime isn’t an interstate reality aside from a scant number of strawman sales (and given that the price of street-sourced guns is about half that of retail, it would also be unprofitable).

TRACE REPORTS: Were “iron pipelines” a thing, there would be a significant number of arrests for gun trafficking and traces conducted by the Bureau of Alcohol, Tobacco and Firearms (BATF). But for the year of our review (2019), it was among the lowest of circumstances, 0.6% of all traces. Heck, “found firearms” accounted for 9.8%, and those recovered after suicides were 2.0%

Hence, there is no top-line evidence for gun running into states with stricter gun laws. But let’s dive deep because we have a few problem states, where more crime guns are imported than sourced locally, and we have an average of 13.4 years from when a gun is retailed out of state and when it is recovered in crime.

Time is of the essence

You read that right. From the time a person passes a background check in a gun store, plops down cash, and takes a gun home with them, to when it is recovered at a crime scene in another state, enough years have passed for your newborn to become a surly teenager.

But aside from outliers (Alaska and Hawaii, who border no other states), the TTC for interstate guns is no different between intra- and interstate gun movement – 13.4 years. This is an interesting data point in and of itself, which indicates that most interstate crime guns are old, and thus unlikely to have been illegally trafficked.

Some studies 1 show that the time span from when a criminal gets a gun and when the cops get it from them is very short – about two months. If “iron pipelines” existed, then the TTC would not be 13.4 years but something closer to 0.17 years (two months). Why the 964:1 ratio nationally, and does it differ greatly from state to state?

Looking at just guns that come from other states (to test the “iron pipeline” notion), we see that the TTC is highly erratic (for the single year we explored). But across the board, there is no statistical correlation between the percentage of crime guns that were imported and how quickly they were used in crime.

Intrastate Crime Guns and Time to Crime 2019

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Intra-state Inter-state Ratio
All Traces 262,181 73,378 3.6:1
<=1yr 44,321 7,475 5.9:1

Looked at nationally, we see that the ratio of crime guns traced is nearly 4:1 for intrastate (retailed within the same state as it was used in crime) and interstate guns (imported from other states). But for guns recovered in under a year from retail sale, the time period where you most likely would find trafficked guns, the ratio rises to 6:1. The younger the crime gun, the more likely it was bought in the state in which it was used for crime.
The question then is, why do imported crime guns take sooooooo long (13.4 years) to be used in crime?

The answer is that they migrated legally.

America, on the move

Americans are a mobile people, and they relocate frequently. The Census Bureau tells us that about 11% of Yanks move every year. (ED: This astounds me. If I have to move more than once a decade, I get grumpy.) Given the number of gun owning households (roughly 43%), that’s around 5% of gun owning households packing up and heading on each year. That divides out to just under six million (minimum) guns legally crossing state lines every 365 days.

You have to be one heck of an enterprising gun trafficker to move six million guns from Texas to New York.

The other element is that people don’t move very far. About 60% move less than 100 miles away and only 15% move to a different state entirely. That pattern would suggest that most interstate guns move legally between neighboring states.

The Census Bureau also tells us that 7% of households that moved in our analysis year moved to a neighboring state. This means that at a rock-bottom minimum – since some gun owning households have more than one gun – 433,000 guns crossed borders between adjacent states.

All Traced Gun in California - 2019
All Traced Gun in Kansas - 2019

Percent of Traced Guns Retailed in recovery State - 2019

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For first-look sake, here is California, which according to one gun control group 2 has the “strongest” gun laws in the country. Compare them with Kansas, chosen for being in the middle of the contiguous 48 states and thus able to import guns from the broadest range of source states. In both states, most of the traced guns were retailed in the same state (California 62%, Kansas 67%) for all guns.

But notice the lighter shaded states. The next largest source is a neighboring state, and this plays out with most of the other states as well (geography makes Alaska and Hawaii relatively immune from short-jump relocations and thus the bulk of interstate guns).

But let us not forget the six stragglers, the states where more than half of traced crime guns were imported, regardless of how they got there. We instantly see something odd, namely that those states tend to be clustered together. Connecticut, Maryland, Massachusetts, New York and New Jersey are wedged up in the northeast and quite some distance from allegedly “lax gun law states.” You might think that perhaps guns are moving between those states, perhaps as part of normal relocations of households.

You might be right.

But tellingly, for guns that were retailed a year or less before they were traced by the ATF, most came from neighboring states. California complains their imported crime guns are due to lax laws in Nevada and Arizona. But most of Kansas’s imported guns come from neighboring Missouri, which has the same degree of gun control. Hence, the strength or weakness of laws in other states does not immediately appear to be a determinate variable, but proximity does.

So, key questions include, “Do guns migrate?,” “Do they migrate in patterns?,” and “Do migrated guns end up being used in crimes?”

This is where it gets complicated and comical.

Guns just don’t walk across country

Legal owners relocating to a new and typically neighboring state explains why the top-line ATF trace numbers look big and are mistakenly used to assert gun trafficking. In trafficking, the goal is to get guns to criminal hands, which is a fast process. How fast? Less than a year, according to one localized study of criminal gun acquisition 3 But guns moving into a new state legally might not leak into the underground for years. The TTC between all sources (intra- and interstate) is about the same, but for guns retailed in the same state where they end up in crime, it is much shorter.

Time to Crime, Intra- and Interstate Guns 2019

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Naturally, there are variations among states, but not much. The ratio of intra- and interstate TTC is between 1.2 and 2.9 (with the average being 1.8) to 1. As the chart shows, whether a gun was retailed in a state or imported, it is unlikely to rapidly fall into criminal hands.

And therein lies the key to unscrambling these numbers. Someone relocating with a legally owned firearm is far less likely to sell it, lose it or have it stolen in the first year than a gun which was trafficked on purpose. Which brings us back to the migrating citizens who don’t migrate far.

Recall that of the 11% of people who move every year, most move less than 100 miles. For those who move into a new state, it would thus be highly probable that they left counties that bordered their new home state. Often cities on state borders are disproportionately large relative to the state population. Thus, the population of state-border counties might be covariant to the number of immigrants into a neighboring state.

According to a 2006 Census Bureau report, there is a 74% correlation between border county populations in neighboring states and relocation into a state. In other words, three quarters of legally migrated guns can be explained just by people moving less than 100 miles into a neighboring state.

The astute reader (that would be you) might be asking, “Why are you using 2006 relocation data?” Because there is a 13-year average TTC gap between when a gun was retailed (2006) and when it was recovered in another state (2019). What we are comparing are those people who moved in 2006 and when their guns were recovered in crimes in whatever state they moved to, which is typically next door.

Where the numbers break down (and federal law prevents us from getting the details) is exactly how many of the traced guns come from those border counties that have a 74% correlation with nominal relocation of citizens. We can tell that on average (excluding Alaska and Hawaii) about 32% of traced interstate guns come from neighboring states. We added an additional data element to gain further insight: the percent of traced guns from neighboring states.

Imported Traced Crime Guns from Neighboring States - 2019

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Interstate Crime Guns, Neighboring States, 2019

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We can see that the spread is broad, ranging from 8% to 65% of interstate crime guns coming from border states. For the top 75% 4 of states by population, we see about a 25% correlation (R2 = 0.25) of interstate crime guns coming from next door. Not a tremendous correlation, but statistically significant.

Aside from Alaska and Hawaii, about 43% of interstate guns come from (on average) five neighboring states, and thus 57% come from 45 other states, which is compelling.

But, alas, this is also incomplete. Recall that the average TTC is over 13 years. That means some crime guns entered the states much earlier. Comparing the migration patterns of one year (2006) with the crime gun traces conducted 13 years later (2019) only shows the most obvious parts of the puzzle, namely that:

  • Neighboring states are the key source for interstate guns.
  • Most (perhaps nearly all) came via normal household relocations.
  • The “iron pipeline” meme is rusting apart.

But, what about New Jersey?

(ED: We have removed the author’s snide remarks in reply to “What about New Jersey?,” which did not translate well without the associated accent.)

In the northeast, there are a knot of states that claim they are on the receiving end of the rapidly disintegrating “iron pipeline.” What we notice right away is that the percent of intrastate crime guns traced in those states is low. In other words, an abnormally low number of crime guns were retailed in those northeastern states.

How low? Of the states where politicians gripe about the decomposing “iron pipeline” – Maryland, Massachusetts, New Jersey, New York and Connecticut – they average a 19% gun ownership rate compared to a national 35% rate. 5 That is nearly half the rate of ownership and can be attributed in part to the historical hostility those states had to guns, with the laws there making ownership difficult. This has two interesting effects:

  1. Lower gun ownership rates means the ratio of interstate guns is artificially inflated.
  2. People moving to adjacent states are less likely to bring guns with them since they own fewer than average.

These two effects, mapped to this tight cluster of northeastern states, makes it look like there is trafficking when there is not. It makes ordinary relocation of legal guns from nonadjacent states look as if something unusual is occurring, though there is nothing unusual about the 13 years it takes these legally relocated interstate guns to become crime guns in those states.


  1. Gangs and Guns: A Task Force Report From The National Gang Crime Research Center; Knox, Houston, Laskey, McCurrie, Tromanhauser; 2995
  2. Everytown Gun Law Rankings, 2023
  3. The Last Link: from Gun Acquisition to Criminal Use; Cook, Pollack, White; Journal of Urban Health; 2019
  4. The lower the population, the less likely border counties make a difference
  5. 2021 National Firearms Survey: Updated Analysis Including Types of Firearms Owned; English; 2022

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