Manhattan’s and Washington’s Populations Nearly Double Every Day With Commuters

Just think of the traffic.

National Journal
Matt Vasilogambros
May 22, 2014, 8:55 a.m.

For most Amer­ic­an cit­ies, the dif­fer­ence in the num­ber of people who live there and the people who only work there is small. People tend to work where they live.

But that’s not the case for some of the lead­ing eco­nom­ic hubs in the coun­try, where em­ploy­ment and com­merce are high. For places like Man­hat­tan and Wash­ing­ton, com­muters can nearly double the pop­u­la­tion dur­ing the day­time.

2013 study from the U.S. Census Bur­eau out­lines which ma­jor counties in the U.S. have the biggest gap between the res­id­ence pop­u­la­tion and the com­muter-ad­jus­ted pop­u­la­tion, which is cal­cu­lated by adding the total area pop­u­la­tion with the total work­ers in the area, and then sub­tract­ing the total work­ers liv­ing in the area. The study uses census data from 2006 to 2010.

The pop­u­la­tion dif­fer­ence is largest in New York County, which com­prises Man­hat­tan. There, the com­muter-ad­jus­ted pop­u­la­tion is 94.7 per­cent lar­ger than the res­id­ence pop­u­la­tion, jump­ing from 1,600,00 to 3,100,00. Most of these people come from oth­er bor­oughs in New York City. Com­muters trav­el­ing from Kings County (Brook­lyn), Queens County (Queens), and Bronx County (the Bronx) to Man­hat­tan ac­count for three of the largest county-by-county pop­u­la­tion flows.

Re­search­ers have ex­tens­ively doc­u­mented the travel habits of New York­ers, and il­lus­trated their move­ments in in­ter­act­ive graph­ics, as seen here on City Lab.

Though it has a third of the pop­u­la­tion of Man­hat­tan, the Dis­trict of Columbia, too, ex­per­i­ences a large jump in its com­muter-ad­jus­ted pop­u­la­tion, shift­ing 79 per­cent dur­ing the day. Most of the com­muters come from neigh­bor­ing North­ern Vir­gin­ia and Mary­land, and they in­crease the pop­u­la­tion from 600,000 res­id­ents to more than 1 mil­lion people dur­ing the day.

Fulton County, Ga., the home of At­lanta, St. Louis, Mo., and Rich­mond, Va., round out the top five counties in the U.S. with the biggest pop­u­la­tion in­crease from com­mut­ing.

The com­muter-ad­jus­ted pop­u­la­tion does not in­clude chil­dren in day care or school, nor does it cov­er uni­versity stu­dents or tour­ists, which would en­com­pass the com­plete day­time pop­u­la­tion. The res­id­ence pop­u­la­tion, too, does not in­clude people stay­ing in ho­tels, which would provide a broad­er pic­ture of an area’s night­time pop­u­la­tion. If those num­bers were in­cluded, the fig­ures would be sub­stan­tially lar­ger for places like Man­hat­tan and Wash­ing­ton. So would the traffic.

Most of the top counties that see the largest pop­u­la­tion in­creases due to com­mut­ing are on the East­ern Sea­board, where there are closer pock­ets of largely pop­u­lated areas. Cit­ies in the Mid­w­est and West Coast are less likely to see big shifts be­cause of lar­ger dis­tances between met­ro­pol­it­an areas.

These data are key for emer­gency re­spon­ders, in­clud­ing the Fed­er­al Emer­gency Man­age­ment Ad­min­is­tra­tion, which use day­time pop­u­la­tion es­tim­ates for dir­ect­ing re­sources dur­ing nat­ur­al dis­asters. It’s also im­port­ant to un­der­stand the needs of a city’s trans­port­a­tion sys­tem.

And with the pop­u­la­tion in­creas­ing and the eco­nomy get­ting bet­ter for many of these places, the gaps might get even big­ger.

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