Taylor Cottam over at Economy Politics is compiling a list of local media reports for tea party attendance across the country on April 15th. Head over there to check it out and send him more articles to fill in cities that he's missed (the list is far from complete!).
Looking the list over, I decided to compile it into a total by being as conservative as I could possibly be. So for instance, when a newspaper reported "over 200" I would count it as 201; when it said "thousands" I would count it as 2000; I counted "a few hundred" as 300 and "several hundred" as 400.
Using that rule and looking through what Taylor has so far (and understanding that I can never add up the same list of numbers twice and get the same sum), I came up with 57,845. So at the very, very least, in all the cities and towns Taylor has figures for, nearly 60,000 (probably more) showed up.
It's probably a lot more, because not only were my estimates extremely conservative as described above, but the dead tree media has a penchant for under reporting attendance at these things, like when it reported 60,000 for the 912 rally in D.C. last year, which demonstrably and irrefutably had over a million marchers.
Also remember Taylor's list is hardly comprehensive. Do visit his post and please send him more data and articles so he can compile a complete list. If we can get together a pretty comprehensive list of cities in the next couple days, we can report the total on Monday, which would make for a great story- a good estimate of the total number of Americans that took to their streets and city halls on tax day to protest.