Census estimates released yesterday reveal that the population of DC’s Ward 6 grew by 9% during most of the last decade. More surprisingly, Ward 1, widely expected to have grown, actually shrank by 3%.

Yesterday the Census Bureau’s American Community Survey released its five-year demographic averages for every neighborhood in the nation. Though the bureau is more famous for its constitutionally-mandated decennial census, it still surveys the nation’s population characteristics in the off-years.

These interim-year numbers are not the basis of Congressional or DC ward redistricting, but they provide an early hint as to where the official Census 2010 numbers are headed. The data released yesterday provide the five-year average for 2005-2009.

Sources: Census 2000 and projections based on ACS 2005-2009

five-year average with estimates for split tracts.

To calculate the ward populations, we took the ACS data by Census tract and allocated it to each ward. Some tracts are split between wards; for those, we estimated the proportion of the population in that tract which lies in each ward. This means the numbers may vary by a percentage point or two in either direction.

Most observers assumed that the areas east of the Anacostia River would continue to shrink in population or at least not keep pace with growth elsewhere, due to less development there this decade. However, their growth pretty closely kept pace with the District’s overall growth of 2.9% in this time period.

It is quite possible the 2010 Census will reveal different changes, but if the pattern holds, it won’t be necessary to significantly expand Ward 7 or Ward 8 west of the Anacostia River, as many expected might happen. In the 2000 census, both wards grew in size; Ward 8 added Historic Anacostia, formerly part of Ward 6, while Ward 7 expanded west of the river to Kingman Park.

While Ward 6, which includes Capitol Hill, H Street, the Navy Yard/Capitol Riverfront, and the Southwest Waterfront, grew the most, it was one of the smaller wards after the last redistricting. The law allows districts to be up to 5% above or below the ideal of one-eighth of the total population. In 2000, Ward 6 was almost the full 5% under, while Ward 4 (the more northern parts of DC) was almost 5% above.

Ward 4 has grown almost exactly apace with the rest of the District, meaning our best guess would put it again just under 5% high, while Ward 6’s rapid growth will likely take it near that threshold but possibly not enough to require redrawing its boundaries either.

Sources: Census 2000 and projections based on ACS 2005-2009 five-year average,

ACS 2009 one-year data, and estimates for split tracts.

Still, there will be changes to these numbers for the 2010 Census. The 5-year ACS data gives a population for DC of about 588,000, up from 572,000 in 2000, but the latest one-year estimates for 2009 estimate a population just about at 600,000, and the full Census is expected to show DC topping that. This means that the five-year data still hasn’t accounted for all of DC’s growth. The unanswered question is, what wards have that not-yet-counted growth?

If the remaining growth hits Ward 1 (U Street, Columbia Heights, Adams Morgan, and Mount Pleasant) at least evenly with the other wards, which is certainly possible with recent development in Columbia Heights, that ward could end up less than 5% below average, making it unnecessary to redraw ward boundaries at all and avoid a very contentious Council debate.

On the other hand, if Ward 1 does keep shrinking at the same rate it did between 2000 and the 2005-2009 average, it could need to get larger, perhaps regaining some of the territory lost to Ward 2 in the 2000 redistricting, such as the blocks south of U Street and west of 14th. Or, since Ward 2 is also below average but Ward 4 is the largest, perhaps Ward 1 would move north toward Petworth and up 14th.

The Census will be releasing their final estimates of DC’s total population (and that of other states) later this month. Tract and block data will follow in early 2011 and redistricting debates should take place in the spring and summer.

You can view our data and calculations in this Google Spreadsheet.

Eric Fidler has lived in DC and suburban Maryland his entire life. He likes long walks along the Potomac and considers the L’Enfant Plan an elegant work of art. He also blogs at Left for LeDroit, LeDroit Park’s (only) blog of record.

David Alpert is Founder and President of Greater Greater Washington and Executive Director of DC Sustainable Transportation (DCST). He worked as a Product Manager for Google for six years and has lived in the Boston, San Francisco, and New York metro areas in addition to Washington, DC. He lives with his wife and two children in Dupont Circle. Unless otherwise noted, opinions in his GGWash posts are his and not the official views of GGWash or DCST.

Rob Pitingolo moved to the DC area in mid-2010 and currently resides on Capitol Hill. He also writes about issues of urbanism, economics, transportation and politics at his blog, Extraordinary Observations.