A fascinating Answer Man column in today’s Post explains (kind of) how your address is determined when your house is built:
The basic method for determining what an address will be in Washington’s close-in suburbs is the grid. Where the house is on the grid determines what number the address should start with.
Montgomery County is in the midst of automating this process. Until then, it’s done manually. Lonnie and his staff consult massive books of bound maps, each one printed on sturdy linen. The corner of each page has a number representing the “coordinate value” for that part of the county. Lonnie looks up the coordinate value in a fraying notebook labeled “Block Number Relativity Tables.”
The system is based on what’s called the WSSC grid, in which a new hundred block starts roughly every 600 feet.
The grid in Montgomery County operates like the one in the District, where the digits increase the farther you get from the U.S. Capitol. (That’s not the case in Howard, where addresses go up the farther you get from Baltimore, the original mother ship for that county.)
Same thing in Fairfax County, said Michael Freund in the county’s Land Development Services division. The grid dictates that addresses start with the 1000 block in the northeastern corner of the county, then increase going west — to the 16000 block — and to the south — to about the 12000 block.
There’s a bit of finesse involved. Development doesn’t march steadily across the landscape. It flares up here and there. Should a subdivision in the middle of nowhere start with 12000 or with 13000? What if something is built nearby later?
“We look at the county as one big puzzle,” Lonnie said. “You just have to see where the pieces fall.”
