Joe Biden spoke earlier at a Cambridge memorial service for slain MIT police officer Sean Collier. Authorities say he was gunned down by the bombing suspects three days after the blasts.
The vice president's wife, who is a runner, brought a pair of her own running shoes and a bouquet of flowers to leave at the memorial near the finish line. She paused and stood quietly for a few moments. She did not speak but waved to people who applauded for her.
On Wednesday afternoon, a few hundred people stood quietly looking at the memorial. The area reopened to traffic earlier in the day.