Although the economy may take a slight hit, and American morale may be slightly lower in the short-term. This tragedy and experience brings us together as Americans. We are all outraged by it, and it helps us realize that we are all on the same team. A team AGAINST whatever disgusting insect did this!
The bombings were tragic but they brought out the best in America. People were giving blood and donating their time, money, and homes to those affected. The bombings ironically make us see how much more good there is in the world than evil. They will also help our governments and first response teams be better prepared for terrorism in the future.
The bombings at the Boston Marathon have made the Americans aware of the need for the continuous awareness of personal and community security. The bombing was not a political statement but the act of cowards hiding in a cloak of fear. Just like the events of 911 the citizens of Boston will rebound and as Americans we will forget about our differences and instead concentrate on makes us Americans and what we value.
No, I don't think the Boston bombings will make America any stronger than it is right now. Realistically, this will be yet another tragedy that will create even more party divides and stronger tensions in Washington. I realize that is probably not a desired stance on this question, but I think that is what is realistic.