It's a traditional thing in the US - at least since 1974.
In 1974, however, the "1812 Overture" came into its own as a pan-American tradition.
That July 4, famed Boston Pops conductor Arthur Fiedler decided to perform the overture with fireworks, real cannons and a coordinated steeple-bell choir to increase attendance at the Pops' summer concerts on the Esplanade, says Bridget Carr, archivist of the Boston Symphony.
Also, the nation's bicentennial was around the corner and the desire to have a spectacular show outweighed Cold War conniptions.
John Philip Sousa's [link|http://www.pbs.org/capitolfourth/starsandstripes.html|The Stars and Stripes Forever] is also traditional during the 4th.
Cheers,
Scott.
