In the 1930s Frederick Law Olmsted Jr. cleared about 250 trees out of Union Square and transplanted 41 more. This bur oak he left exactly where it was. It has grown on this spot since at least 1850, when the United States Botanic Garden moved its greenhouse collections onto this ground, which makes it one of the very few trees on the Capitol campus that predates the twentieth century redesign of everything around it. The Architect of the Capitol puts it at 150 to 175 years. The National Park Service witness tree survey is more careful and says the true age is simply unknown, noting only that aerial photographs taken at the Grant Memorial's dedication in April 1922 already show a large, well developed tree. Read 175 years as a floor rather than a figure. What it has outlived: the demolition of the old Botanic Garden buildings in 1930, Olmsted's redesign of the square, and the 1971 installation of the Capitol Reflecting Pool, which took out most of the trees that were still standing. When surveyed in November 2006 it measured 125 feet tall, with an 85 foot crown and a trunk 165 inches around, the largest bur oak recorded in Washington. Bur oaks can approach a thousand years and are not considered mature until 200 or 300. By the standards of its own species, this giant is still young.
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Getting there
Union Square, U.S. Capitol Grounds, southeast of the Ulysses S. Grant Memorial, along 1st St, Washington, DC
You can recognise it as the large oak left standing when the square around it was cleared and replanted in the 1930s. It stands in Union Square, southeast of the Grant Memorial.
Free, fully public. Stands on open U.S. Capitol Grounds parkland (Union Square), no restriction, viewable and approachable year-round.
On the National Mall side of the Capitol grounds; roughly 10-15 min walk from Capitol South or Union Station Metro (both serve multiple lines).
The line is our estimate of how much there is to see, not a measurement. Typical for this species where this tree stands; exact weeks shift with the year.
Sources
Where the facts on this page come from. The story was written with AI from these sources, and readers who know the tree correct it.