Literature Review
Does public transit increase crime in nearby areas? Or does it put more eyes on the street and make things safer? Researchers have gone back and forth on this for a long time. The honest answer is that it depends. It depends on how many stations are nearby, how busy they get, what the entrance looks like, what time of day you measure, and how you draw your study boundaries. No single answer fits every situation.
Two theories keep showing up when people study this. Routine activities theory says crime needs three things to happen: someone who wants to offend, a suitable target, and nobody around to intervene. Crime pattern theory adds that offenders do not wander randomly looking for victims. They commit crimes in places they already know, along routes they already travel. Subway stations fit both ideas well. They pull in strangers from across the city. People rush through without paying much attention to each other. That creates opportunity for theft, pickpocketing, things like that. But it also puts more potential witnesses on the street. So which effect wins? That is what researchers try to figure out.
Li and Kim (2022) studied this in New York City. They used something called egohoods. Think of them as overlapping quarter-mile circles centered on Census blocks. They wanted to know whether having more stations nearby, or having more riders passing through those stations, correlated with crime. Both did. But the relationship was not straightforward. More stations seemed to push up some crimes. Ridership effects bounced around depending on the offense type. And areas with lots of retail? Those showed stronger patterns. So here context clearly mattered.
Su, Li, and Qiu (2023) did something different. They wanted to know what the area right outside each subway entrance actually looks like. So they grabbed images from Google Street View and built a machine learning model that could score how each entrance looked. How good was the lighting? Were there benches? Did the area look like a mess? Turns out, the cleaner and brighter the entrance, the less crime they saw nearby. The entrances that looked cluttered or felt cramped? More crime (Su et al., 2023). Even small details like where they put a bench or how bright the lights were seemed to matter.
Irvin-Erickson and La Vigne (2015) looked at the DC Metro instead. They asked a slightly different question. Does a station generate crime by creating easy targets, or does it attract offenders who were already planning to do something? Their answer: depends on when you look. Rush hour patterns were different from late-night patterns. A single station could play both roles depending on the time. So, you cannot just say stations cause crime or stations prevent crime. It is more complicated than that.
So how do researchers actually measure station access? There are basically two ways to do it. The first is structural. You count how many stations fall within a certain distance of each location. This tells you about opportunity and how connected a place is. The second way focuses on flow. You measure how many people actually enter and exit those stations. This tells you about exposure. Here is the thing though. The two measures behave very differently over time. Station counts barely budge from year to year. Ridership? That swings around. Service cuts, special events, seasons, big disruptions like a pandemic. All of it shows up in ridership numbers. If what really matters is how many people are walking around, then ridership probably captures that better than station counts. Studies that only look at where people live might be missing the point. Near a busy station, the commuters passing through can easily outnumber the people who actually live there (Kim, Ulfarsson, & Hennessy, 2007; Esfandyari, 2020).
Why does this distinction between structure and flow matter so much? Station counts tell you about fixed opportunity. This station exists here, that station exists there. Ridership tells you about actual people moving through. And crime opportunity depends on who is actually present, not just who lives nearby. Criminologists call this ambient population. A commercial block might have almost nobody living on it but thousands of people during the workday. Ridership picks that up. It records how many potential victims and potential witnesses pass through in a given period. Station counts miss the short-run changes. Ridership catches it. And when your geographic unit is small, like a quarter-mile circle, ridership helps deal with edge problems too. It reflects who is actually hanging around near boundaries, not just who officially lives inside the circle (Li & Kim, 2022; Kim & Hipp, 2020).
How you draw boundaries matters more than most people think. Spatial analysts call this the modifiable areal unit problem. Basically, change how you draw the lines and your results change, even if nothing in the real world changed. Quarter-mile egohoods are a reasonable compromise. Small enough to capture what is happening locally. Large enough to smooth out random noise from crimes that happen right at the edge. Li and Kim (2022) used them for New York and got sensible results. You could go smaller, like street segments, and see finer patterns. But then you fragment context. Move the boundary a little bit and suddenly your estimates shift, not because anything real happened but because your measurement changed (Kim & Hipp, 2020). That is why being transparent about your units matters. Report them clearly. Run checks at different scales. And report results as elasticities so people reading your work can compare it to other studies.
How you measure distance adds another wrinkle. Straight-line buffers are simple. Draw a circle, see what falls inside. Easy to compute, easy to explain. But people do not actually walk through rivers. Or highways. Or fenced-off rail yards. Network distances that follow the actual street grid might capture real movement better, especially in a city like New York where water surrounds you on multiple sides. Which method you pick can change which crimes end up inside your unit and which ones fall outside (Ferreira, João, & Martins, 2012; Setiawan et al., 2019). Most big studies stick with straight-line buffers because they are practical. Then they check whether results hold up when they tweak the radius a bit.
Not all crimes respond the same way to transit activity. Theft probably goes up when crowds grow. More wallets to grab, more anonymity to hide in. Assault might depend more on alcohol, social tensions, or whether police are around. Li and Kim (2022) found that patterns jumped around across offense categories. Su et al. (2023) found that fixing up entrances helped some crimes more than others. And crime clusters for reasons that have nothing to do with subway stations at all. Hot spots tend to stay hot year after year. Near-repeat dynamics mean one crime makes another nearby crime more likely for a while. That creates clustering even after you account for stations being there. Which is why you need to test for spatial autocorrelation. If it shows up in your residuals, spatial lag or error models can help you figure out whether that clustering is affecting your estimates (Anselin, 1988; Elhorst, 2014; Roy & Chowdhury, 2023).
Proving that transit actually causes crime changes is hard. Really hard. Cross-sectional studies compare different places at one moment in time. But some neighborhoods have always had more crime, for reasons that have nothing to do with whether a subway station sits there. Policing intensity varies from block to block. Reporting rates vary. People in some areas call 911 more than people in others. Reverse causality could also be happening. Maybe crime goes up first, and then ridership drops because people avoid that station. Or maybe safety investments follow ridership growth, and that hides whatever effect the crowds were having. Station placement is not random either. Transit agencies put stations where people already want to go. That means station areas are different from non-station areas in ways that also predict crime.
Fixed-effects models help deal with some of this. Instead of comparing different neighborhoods to each other, you compare each place to itself over time. If something about a neighborhood stays constant, like its income level or building density, that gets filtered out even if you never measured it directly (Allison, 2009). But fixed effects do not solve everything. If local trends happen to line up with ridership changes, you still have a problem. And when spatial clustering shows up in the residuals even after controls, you need to dig deeper. Spatial lag or error models can help you figure out if that leftover clustering is biasing what you found (Anselin, 1988; Elhorst, 2014).
The modeling choices researchers make reflect all these headaches. Some studies treat crime as a count. They use Poisson or negative binomial regression because those handle situations where lots of places have zero crimes or just a few (Cameron & Trivedi, 2013). Other studies take the log of crime, usually log(1 + count), which lets you read coefficients as elasticities. Log transforms work nicely with two-way fixed effects. When crime is not mostly zeros, both approaches usually point in the same direction and give you roughly similar magnitudes. A lot of researchers run both and treat one as a sanity check on the other.
What is around a station shapes whether it raises or lowers crime. Lots of retail nearby? Maybe more targets walking around with shopping bags. Poor sight lines from overgrown bushes or unusual architecture? Maybe less informal surveillance. Good lighting? Maybe more people feel comfortable, and that discourages offenders. Li and Kim (2022), Sadeek et al. (2019), and Su et al. (2023) all found that the surrounding environment matters a lot. Stations are not all the same. What happens around them depends on what else is there.
The pandemic makes this particular time period strange. Between 2020 and 2024, ridership fell off a cliff and then slowly climbed back. Work patterns changed dramatically. Policing strategies shifted. Any study covering these years has to deal with the fact that huge shocks hit every neighborhood at once. Year fixed effects soak up a lot of that shared variation. They help you see what changed within specific places versus what changed everywhere. But still. Generalizing from pandemic years to normal years is risky. The patterns might not transfer.
Two gaps in the existing research motivated this study. First, most prior work uses cross-sectional snapshots. Those mix up permanent differences between places with actual changes happening over time. Second, not many studies have combined egohoods with panel data and fixed effects for New York City specifically. Li and Kim (2022) brought the egohood idea to this setting, but they only looked at one point in time. This study follows the same egohoods across five years. It pairs a structural measure, whether a station is present, with a flow measure, how many riders passed through that year. It uses two-way fixed effects to focus on within-place variation while controlling for what changed citywide each year. And it tests whether spatial clustering in the leftover errors might be biasing the estimates. The goal is to get clearer on when subway activity lines up with crime changes, and when it does not.