Make way

Roused from the couch by a din, sirens, thunderous motorcycles, I went to my front door to discover an incredible motorcade making it’s way up my street just a few moments ago. Numerous police motorcycles, state police cars, secret service, and at least 6 Greyhound buses were rumbling by my house on lovely Walter Reed Drive in Arlington, headed into the city. I can only assume it was John Kerry, who’s scheduled to campaign here.
In fact, as a native Washingtonian who’s lived here his entire life, I can’t remember ever seeing a motorcade like this before, not even for a sitting president!
My big question is this: why did the motorcade rumble by my humble suburban home, when interstate 395 leading into downtown Washington is mere blocks away? Was he trying to avoid the traffic at the bridge?