Washington National airport, the close-in airport for DC, has strict rules for routing landings and departures. This is both the result of noise restrictions but also for security. Planes come close to national monuments and even the White House. Deviate and fighter jets can scramble. Miss and approach and you can get sent to Dulles airport.
Most of downtown D.C. below 18,000 feet is prohibited airspace. There’s a narrow path pilots have to fly, that’s pretty cool for passengers. The River Visual approach causes aircraft to hug the Potomac and turn just before landing.
Flights taking off to the North climb quickly and turn left — one doesn’t want to get shot down approaching the Washington Monument and White House!