Gov. Jay Nixon on Monday signed a law updating state fireworks laws to comply with newer federal regulations.
Nixon said the new law, supported by the state fire marshal, will help ensure continued safety and enjoyment of community July 4th displays.
In 2009, the U.S. Transportation department changed the way it defined, and classified, fireworks for labeling, shipping and possession.
The federal law changed, in some cases, the amount of explosives contained in the fireworks.
Sen. Mike Kehoe, R-Jefferson City, sponsored the bill changing Missouri's law, which until now had included references to the pre-2009 designated amounts.
The measure cleared the Senate on a 33-0 vote on May 1, then was passed by the House on a 125-0 vote on May 18 - the legislative session's last day to pass bills.
Lawmakers also approved an emergency clause, so the measure became the state's new law as soon as Nixon signed it.
"Celebrating America's birthday with community fireworks displays is a time-honored tradition in towns large and small across Missouri," Nixon said in a statement. "This new law will help ensure that the displays continue to be both safe and enjoyable."
Jefferson City's Salute to America program sponsors have said the new law also lets them include larger, 16-inch fireworks for the first time, which, they say should improve the holiday display.
Kehoe and other supporters said during the legislative debate that the bill affects only commercial displays, and doesn't change what citizens can and cannot buy at a retail fireworks outlet.