An enumeration district is a geographic area determined for purposes of taking the census. In one city there may be many enumeration districts, so once you enter a city, county, or state, you can narrow your results by entering street level information, or investigate enumeration district maps, or descriptions.
P wave. 1. a longitudinal earthquake wave that travels through the interior of the earth and is usually the first conspicuous wave to be recorded by a seismograph. Also called primary wave. Compare L wave, S wave. The P wave is admitted to be the wave of auricular contraction. p wave.
# P-Wave: These are called 'P' for Primary Wave. They are the ones that travel fastest and thereby are usually felt first. They are basically sound waves that travel thru the earth from the epicenter of an earthquake. Physics types know this as a longitudinal wave.