Running between N and O St. is a road that is mostly called Dumbarton St. However, in more than a few places it is called Dumbarton Ave. For instance, Dumbarton United Methodist Church uses the address “3133 Dumbarton Avenue”. Also, several homes are labeled with “Dumbarton Ave.” Hell, as shown above, Google Maps can’t make up its mind and just calls it both.

So what’s the deal? Why the split personality? For the answers, follow GM back through the 18th and 19th centuries after the jump:

The name “Dumbarton” made its way to Georgetown via Scotsman Ninian Beale who was granted 75 acres from Lord Baltimore in 1703 in what would become Georgetown. Beale named the land tract “The Rock of Dumbarton” after a massive rock located in Dumbarton, Scotland. This name carries on in Dumbarton House, Dumbarton Oaks, and of course Dumbarton St./Ave.

But what’s the right name? Probably street, but it’s complicated. First of all, for the first half of its existence the name was “Dunbarton” not “Dumbarton”. As seen from this map from 1851 (the earliest GM could find displaying either name) the road was called “Dubarton St.”:

This spelling and designation continued through 1873:

and at least through 1878:

In 1871 Georgetown’s charter was revoked by Congress and the city was absorbed into District of Columbia, thus bringing to an end the autonomy of the City of Georgetown. By 1880, the street names of Georgetown were changed to be consistent with the rest of D.C.’s street grid. Thus east-west streets like Gay and Beall were changed to N and O, respectively; and north-south streets like Congress and High St. were changed to 31st and Wisconsin, respectively. Some streets, though, didn’t fit in with the grid system and so they kept their names. Dunbarton/Dumbarton was one of those.

Interesting side note: for a time after the revocation of Georgetown’s charter, the neighborhood was officially referred to as “West Washington”:

According to Washington Post archives, the name “Dunbarton Avenue” begins to show up in their pages around 1881. Here’s an example:

While the Methodists are celebrating the year 1884 as a centenary occasion, it is interesting to know that in Georgetown, now called West Washington, Methodism was founded in 1792, or 112 years ago. This fact is made public in an interesting pamphlet, entitled “A Centennial Sketch of Methodism in Georgetown, D.C.,” and compiled by J.W. Kirkley an official member of the Dumbarton-avenue M.E. Church, Georgetown. – Washington Post – Dec. 28, 1884

Here you can see an 1886 map where the road appears a “Dunbarton Avenue”:

GM doesn’t have proof that the street renaming was what led to this, but if you look at the map above you’ll see that Olive St. was called “Olive Ave.” all of the sudden as well (not seen in this detail, but Potomac St. was listed as Potomac Ave. too). Maybe there was a decision to distinguish the non-conforming streets with the name “avenue”. This answer is still unsatisfying since Grace St. and Water St. were still listed as such.

Regardless of the objective, it appears that some change in designation occurred apparently the exact time of the street renaming. Additionally, by 1909 the “M” made its way into the name on maps, although as shown by the quote above, it had been used somewhat interchangeably by the Post for a while before that (oddly enough, the County of Dumbartonshire Scotland, where the Dumbarton Rock is located, actually changed its name to Dunbartonshire around the same time):

As late as 1942, maps listed the road as “Dumbarton Avenue”:

Despite this surge of “Avenue”, at some point between 1942 and today it appears that the District came down on the side of “Dumbarton St.” The street signs say “St.” and the property tax rolls list homes on Dumbarton St. (although even that has two “Dumbarton Ave.” addresses!) A call to the Georgetown Post Office confirms that at least they think its Dumbarton St., however, they said that a letter addressed to Dumbarton Ave. will be delivered just as well.

So it seems that the long story of a short road has ultimately led to “Dumbarton St.” with only a few echoes around of its brief foray into avenuehood.

For what it’s worth, GM prefers Dumbarton Avenue. What do you think?