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The auto numbering CSS used is found here:
CSS is in the section titled "Easy method of auto numbering of table rows".
Click the 4/20 or GMM column header a few times to put all the cities with 420 events or GMM events at the top, and in alphabetical order.
It seems to work best when one first clicks the City column header until the cities are back in A-Z alphabetical order. Then go to the GMM or 420 column.