What Goes into the Massive Fireworks Displays on the 4th of July?

Every 4th of July in many cities all over the United States there are massive fireworks displays for thousands to see. One of the biggest is right in our backyard in Boston, Massachusetts. The Independence Day celebrations in Boston are so large that it takes around 4 days to install the explosives but much longer for the pyrotechnician to plan and design the firework display to make it look amazing and go off seamlessly.