What a scan is
A scan reads Google Maps at 121 points laid out as an 11×11 grid, centred on the store's own Google pin. The grid reaches 2 miles out from the pin in New Jersey, Rhode Island and Washington DC; in Nevada, 2 miles in Clark County and the Reno area, 5 miles elsewhere; in California, 2 miles in the 12 metro counties of Greater Los Angeles, San Diego, the Bay Area and Sacramento, 5 miles elsewhere. Everywhere else we scan, it reaches 2 miles in the 234 core counties of the New York City, Buffalo, Rochester, Boston, Worcester, Providence, Detroit, Grand Rapids, Chicago, St. Louis, Seattle, Portland, San Juan, Hartford, Philadelphia, Baltimore, Washington DC, Pittsburgh, Richmond, Virginia Beach, Miami, Tampa, Orlando, Jacksonville, Columbus, Cleveland, Cincinnati, Charlotte, Raleigh, Memphis, New Orleans, Kansas City, Minneapolis, Oklahoma City, Tulsa, Dallas-Fort Worth, Houston, San Antonio, Austin, Denver, Salt Lake City, Phoenix, Tucson, Honolulu, Atlanta, Louisville and Birmingham metro areas and 5 miles elsewhere, all of Maine, Vermont, West Virginia, Iowa, North Dakota, South Dakota, New Mexico, Montana and Alaska included. Each store is scanned for “dispensary near me”, “cannabis near me” and “weed near me”, one grid per search.
At every point we record the order of the listings a shopper standing there is shown. Every point reads the first 20; the centre point reads the whole list, so a store's position at its own door is known however deep it sits.
Lists for “weed near me” ran about 8 listings a point (median), against about 20 for “dispensary near me” and “cannabis near me”; the centre point, which reads Google's whole list, holds about 8 too. Every scan runs the same settings, so the short lists are Google's own, and a store page says how many listings Google showed rather than “not in the top 20”.