Washington DC has long been known as the "City of Trees" because of its diverse and historic tree population. From the famous flowering cherry trees around the Tidal Basin to the southern magnolias at the White House and the 4000+ trees on the Capitol grounds, it's part of what makes the city so beautiful.
Years of neglect left the tree canopy much reduced, but a program was started by Casey Trees in 2002 to plant new trees across the city with an eventual goal of a 40 percent tree canopy.
For this year, Casey's Tree Report Card gives DC an A minus. The tree canopy increased last year from 36 to 38 percent, bringing the city within two percentage points of its goal.
Part of the program is to plant diverse trees throughout the city to avoid rapid deterioration from potential new pests and diseases. I just noticed a new tree the other day in a Northwest DC neighborhood, a pink-flowering red horsechestnut. I was totally unfamiliar with it, but's it's a lovely specimen.
Aesculus x carnea 'Fort McNair' is a 30 x 30' small flowering tree with a rounded form, great for small landscapes. The long clusters of pink flowers have yellow throats and attract hummingbirds and bees. The dark green palmate leaves have a tropical effect and are attractive year-round. Hardy in USDA Zones 4-7.