Chicago Parking Permit Map

This repository contains the main script used to generate an interactive HTML map of Chicago parking permit zones from the CSV in the project's data folder.

The current entry point is:

• src/create_parking_permit_map.py

The script geocodes the address ranges in the source CSV, draws each permit segment on a Folium map, and adds browser-side filtering and address search controls.

What the program does

• Reads parking permit zone rows from ../data/Parking_Permit_Zones_20260313.csv
• Geocodes the low and high address for each row
• Draws each row as a colored line segment on a map of Chicago
• Adds UI controls for:
  • status filtering
  • buffer filtering
  • ward filtering
  • address search
• Reuses a JSON geocode cache so repeat runs are faster

Why this program exists

When checking to see whether an address is part of a residential permit parking zone, the City of Chicago provides the following resource: https://ezbuy.chicityclerk.com/zone-lookup

This site allows you to enter an address and it will tell you the zone if it is in one. You must have an address in mind and cannot easily discern the boundaries of the zones.

There did not exist (to my knowledge) a visual resource showing all zones on a map -- there are some wards which provide maps of the zones but they can be in my experience pretty tricky to find.

So I made one!

Data source

The parking permit zone data used is from: https://data.cityofchicago.org/Transportation/Parking-Permit-Zones/u9xt-hiju/about_data

Notes

Output

The output is not perfect -- different geocoders will give varying accuracy. I have only used nominatim and arcgis -- these geocoders sometimes don't give accurate coordinates for the high or low addresses (especially when the address doesn't physically exist) which results in lines that are far too long on the map. If anyone has access to another geocoder and wants to try, feel free to share the cached output!

Geocoders

Only nominatim and arcgis have been verified to work -- while there is implementation for others, it is not guaranteed to work

ArcGIS provides cleaner output than Nominatim.

AI use

GitHub Copilot was used to develop this program.

Prerequisites

• Python 3.10 or newer is recommended
• Internet access for geocoding
• A Python virtual environment is recommended

Install dependencies

From the repository root:

python -m venv .venv
.\.venv\Scripts\Activate.ps1
pip install -r .\src\requirements.txt

Quick start

From the repository root:

python .\src\create_parking_permit_map.py

By default, the script uses:

• Input CSV: data/Parking_Permit_Zones_20260313.csv
• Output HTML: output/parking_permit_zones_map.html
• Cache file: data/geocode_cache_chicago.json
• Geocoder: nominatim

When the run finishes, open the generated HTML file in a browser.

Common examples

Process only a few rows for a quick test:

python .\src\create_parking_permit_map.py --max-rows 10

Write to a custom output file:

python .\src\create_parking_permit_map.py --output .\output\parking_permit_zones_map_test.html

Use ArcGIS instead of Nominatim:

python .\src\create_parking_permit_map.py --geocoder arcgis

Tune geocoding rate limiting:

python .\src\create_parking_permit_map.py \
  --geocoder nominatim \
  --geocode-min-delay-seconds 1.5 \
  --geocode-timeout 15 \
  --geocode-max-retries 3

Supported geocoders

The script supports these --geocoder values:

Only nominatim and arcgis have been verified to work -- while there is implementation for others, it is not guaranteed to work

• nominatim (verified)
• arcgis (verified)
• photon
• google
• here
• mapbox

API-key providers

Some providers require environment variables.

Google:

$env:GEOCODER_GOOGLE_API_KEY = "your-google-key"
python .\src\create_parking_permit_map.py --geocoder google

Here:

$env:GEOCODER_HERE_API_KEY = "your-here-key"
python .\src\create_parking_permit_map.py --geocoder here

Mapbox:

$env:GEOCODER_MAPBOX_API_KEY = "your-mapbox-key"
python .\src\create_parking_permit_map.py --geocoder mapbox

Command-line options

The most useful options are:

• --csv: path to the source CSV file
• --output: path for the generated HTML map
• --cache: path to the geocode cache JSON
• --max-rows: limit processing to the first N rows for testing
• --geocoder: choose the geocoding provider
• --geocode-timeout: timeout per request in seconds
• --geocode-min-delay-seconds: minimum delay between requests
• --geocode-max-retries: retry count for failed requests
• --geocode-error-wait-seconds: delay before retrying after an error

Show the built-in help:

python .\src\create_parking_permit_map.py --help

Output files

Primary outputs:

• HTML map file in output/
• Geocode cache file in data/

The zone data is embedded within the HTML map so it is completely portable. No need for internet access.

The cache is reused across runs and is namespaced by geocoder provider, which helps avoid mixing results from different providers.

Notes

• The first full run can take a while because every uncached address must be geocoded.
• Subsequent runs are much faster if the cache file is preserved.
• If many rows are skipped, try a different geocoder provider.
• --max-rows is mainly useful for quick testing before running the full dataset.

Related files

• requirements.txt: Python dependencies for this script
• run_command.txt: example PowerShell command