Geocoding addresses

[vingkan]

We have several product features where it would be useful to geocode: convert an address to longitude/latitude coordinates and other geographic information.

For example:

• Datasets in offline pipeline that have address or zip code but not other geo fields could be mapped to coordinates and community areas
• Pages on the frontend could allow the user to enter their address or zip code and then see results for their community area
• Pages on the frontend could show pins on a map for the coordinates of a record

We would like to find a free geocoding service, I think I found two a few months ago that could work:

• Chicago geocoding service
• Census geocoding service

Below are my messy notes from playing around with those. I can explain how to get these into Python code and add them into our codebase.

We could do geocoding in the offline pipeline or in the backend API or both depending on the use case.

fetch(
    `https://api.chicago.gov/els/forwardgeocoding/rest/geocode_3`,
    {
        method: "POST",
        headers: {
            'Accept': 'application/json, text/javascript, */*; q=0.01',
            'Accept-Encoding': 'gzip, deflate, br',
            'Accept-Language': 'en-US,en;q=0.9',
            'Authorization': 'Basic ZWxzX2NsaWVudF93YXJkZ2VvOnR2S0xANFM2N2Fw',
            'Connection': 'keep-alive',
            'Content-Type': 'application/json',
            'Host': 'api.chicago.gov',
            'Origin': 'https://gisapps.chicago.gov',
            'Referer': 'https://gisapps.chicago.gov/',
            'sec-ch-ua': '" Not A;Brand";v="99", "Chromium";v="90", "Google Chrome";v="90"',
            'sec-ch-ua-mobile': '?0',
            'Sec-Fetch-Dest': 'empty',
            'Sec-Fetch-Mode': 'cors',
            'Sec-Fetch-Site': 'same-site',
            'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.93 Safari/537.36',
        },
        body: JSON.stringify({
            ForwardGeocodeServiceInput3: {
                "systemId": "WARD_LOOKUP",
                "offsetFt": "20",
                "fullAddress": "2345 S Michigan Ave",
                "getGeos": {
                    "geographyName": "CENSUS_TRACT"
                }
            }
        }),
    }
).then(async (res) => {
    const data = await res.text();
    console.log(data);
}).catch((err) => {
    console.error("Something went wrong:");
    console.log(err);
});

let address = "2345 S Michigan Ave, Chicago, IL";
fetch(
    `https://geocoding.geo.census.gov/geocoder/locations/onelineaddress?format=json&benchmark=2020&address=${encodeURIComponent(address)}`
).then(async (res) => {
    const data = await res.json();
    console.log(data);
}).catch((err) => {
    console.error("Something went wrong:");
    console.log(err);
});