City Open Data Portals

Open data portals were built for civic transparency and journalism. They happen to be excellent investigative sources, because a city publishing its operational records is publishing a great deal of dated, addressed, vehicle-linked detail that would otherwise take a records request to obtain.

New York City runs the largest and best of them, so it’s the example here. The approach transfers — Chicago, Los Angeles, Boston, Seattle, Austin, San Francisco and several hundred others run comparable portals, most on the same underlying platform with the same query interface.

NYC Open Data homepage headed Open Data for All New Yorkers with a search box — NYC Open Data. The search box takes a dataset name, not a person.

The parking dataset

The one to know is Open Parking and Camera Violations. It runs to tens of millions of rows and each one carries plate number, plate state, license type, issue date, violation time, the violation code, the fine amount, the location and the issuing agency.

Charts summarising parking and camera violations broken down by violation type, issuing agency and status — The portal generates its own summaries. Useful for orientation, not for casework.

The filters are what you actually want. Query the plate and you get every citation issued to that vehicle, in order, with where and when. That’s a movement history for a car, assembled from a public source, at no cost.

Tabular view of the violations dataset with columns of records returned by a filtered query — The table view. Filter it down, then export the result as CSV.

There’s also a View Summons link on many records, which produces images of the citation itself, front and back. It shows the plate, the location, the vehicle details and the officer’s notes.

What it will not give you

The registered owner. That is DMV data, protected by the Driver’s Privacy Protection Act, and it requires a permissible purpose through the proper channel. The open data tells you about the vehicle, not the person.

Which is still worth a great deal. If you already have a plate from another source, the citation history establishes where that vehicle has been and when — and a pattern of tickets on the same block at the same hour is a residence or a workplace whether or not anyone has told you so.

Working it in practice

Plate to pattern. Filter on the plate, sort by date, map the locations. Repetition at the same address is the finding
Address to plates. Filter on a street and see which vehicles are repeatedly cited there. Useful when you know the location and not the car
Date bounding. A citation is a hard timestamp for a vehicle at a place. On the right day, that’s a fact you can put in a report
Export it. Every one of these portals will produce CSV. Do the analysis in a spreadsheet rather than in the browser

The rest of what cities publish

Parking is the well-known one. The others are frequently more useful and get looked at less:

Dataset	What it gives you
Building permits	Owner or contractor name, property address, work described, dated. Money being spent on a property
Housing and health inspections	Landlord and management company names tied to addresses
311 service requests	Complaints by address, with dates. Establishes occupancy and conditions
Business licenses	Trading names, addresses, responsible parties
Restaurant inspections	Operator names and addresses, inspected regularly
Payroll	Municipal employees by name, title and salary
Vehicle and taxi registrations	Licensed drivers and vehicles, where the city licenses them

Building permits are the sleeper. Somebody who claims they can’t pay, with a $180,000 permit filed on a property last spring, has a problem that a dataset just handed you.

Finding the portal for a city

Search the city name with open data. Most run on Socrata, which means the same query interface, the same filtering and the same CSV export you see here. A number of states and counties run their own as well, and county-level data is where property, permit and court information tends to live.

These portals don’t replace a records request. What they do is answer the questions that would otherwise become a request — instantly, at no cost, and without putting your name in front of the agency.