A city never sleeps?  Well, some do, at least according to a fairly recent report from the Census Bureau. 

October 21, 2005

Company: U.S. Census Bureau
Industry: Demographic Data
Location: Washington, DC, United States of America

If it seems a little crowded on weekdays in cities like Washington,
D.C.; Irvine, Calif.; Salt Lake City, Utah; or Orlando, Fla.; it's not
your imagination. Among cities with 100,000 or more people, these four
show the highest percentage increases in population during the day as
opposed to their resident population.

The findings come from the first-ever U.S. Census Bureau estimates of
the daytime population for all counties and more than 6,400 places
across the country, based on Census 2000 data.

The concept of the daytime population refers to the number of
people, including workers, who are present in an area during normal
business hours, in contrast to the resident population present during
the evening and nighttime hours.

“Information on the expansion or contraction experienced by different
communities between nighttime and daytime is important for many
planning purposes, including those dealing with transportation and
disaster relief operations,” said Census Bureau Director Louis
Kincannon. “By providing information on the number of people not living
in the area, but nevertheless greatly affected by the event, the data
can provide a clearer picture of the effects of disasters such as
Hurricanes Katrina and Rita.”

The places where the largest percent increases in daytime over
nighttime populations occur tend to be those with small resident
populations. For example, among medium-sized cities, Greenville, S.C.,
has a daytime population that is 97 percent higher than its nighttime
population. Palo Alto, Calif., increases by about 81 percent, and Troy,
Mich., by 79 percent. Among very small places, gains approached 300
percent in Tysons Corner, Va. (292 percent); and El Segundo, Calif.
(288 percent).

Other highlights:

• New York City has the largest estimated daytime population, at more
  than 8.5 million persons. The increase of more than half a million
  people over the nighttime population is bigger than that found in any
  other area. However, the 7 percent increase puts New York in the middle
  of the pack on percentage change among cities with more than a million
  residents.
  
• The second highest numeric daytime increase is in Washington,
  D.C., where 410,000 workers boost the capital's population by 72
  percent during normal business hours.
  
• Other big cities with large daytime gains are Atlanta (62
  percent), Tampa (48 percent) and Pittsburgh and Boston (both around 41
  percent).
  
• Typical examples of sizable expansion of daytime populations
  in small cities can be found in places such as Paramus, N.J.; Redmond,
  Wash.; and Beverly Hills, Calif., among others.
  
• About 250,000 people worked in New Orleans prior to Hurricane
  Katrina. Almost 150,000 of these workers were residents of New Orleans,
  but the remaining 100,000 lived outside the city.
  
• One of the most extreme examples of daytime population
  increase is Lake Buena Vista, Fla., which has almost no permanent
  residents but swells to an employment center of more than 30,000 people
  during the day.