I musta missed the post with the Google Map of the GNRs, my apologies.
And I knew that the other map was based on ZIP -- then again, even Google Maps has my house off by about a block when I give it the address. The base data appears to be based on equal spacing between block 100's -- I'm at 1822, but the house on the other side of my corner is 1900, so it puts me about a fifth of the way from 1800 to here.
Aside from the abuse potential, having a closer mark than zip code would be nice to plan LTH block parties. I wonder if it takes Zip+4?
(edit - no, it doesn't take Zip+4)
What is patriotism, but the love of good things we ate in our childhood?
-- Lin Yutang