In one year, the Tea Party has gone from a wink-wink dirty joke to a semi-organized political movement that has successfully gotten candidates elected to office. Thousands of Tea Party activists are expected to turn out today—tax day—in protests around the country.
To track the growth of the movement, Slate collected information from the 575 groups on Meetup.com that identified both "tea party" and "politics" as interests. (Including "politics" in the search eliminates false positives like the group Ms Patti's Little Princess Tea Parties.) Of those 575, about 450 make their meeting schedule public. We took this information and mapped it over time. The data is displayed as a heat map, where brighter colors represent a higher density of events. Most of the meetings represented on the map are smaller ones not involving Sarah Palin.
While this information is far from comprehensive, the sampling paints a picture of a sustained and growing political insurgency with obvious pockets of near-constant activity. The timeline at the top can be dragged to a specific date.