On this day in 1776, the Declaration of Independence was approved by the Continental Congress, setting the 13 colonies on the road to freedom as a sovereign nation. As always, this most American of holidays will be marked by parades, fireworks and backyard barbecues across the country.

In July 1776, the estimated number of people living in the newly independent nation was 2.5 million. The nation’s estimated population on this July 4 is 31.7 million.

In 2010, the dollar value of U.S. imports of American flags was $3.2 million. The vast majority of this amount — $2.8 million — was for U.S. flags made in China.

The value of fireworks imported from China in 2010 was $190.7 million, representing the bulk of all U.S. fireworks imported ($197.3 million). U.S. exports of fireworks, by comparison, came to just $37 million in 2010, with Japan purchasing more than any other country ($6.3 million).

Thirty-one places have “liberty” in their names. The most populous one as of April 1, 2010, is Liberty, Mo. (29,149). Iowa, with four, has more of these places than any other state: Libertyville, New Liberty, North Liberty and West Liberty.

The chance that the hot dogs and pork sausages consumed on the Fourth of July originated in Iowa. The Hawkeye State was home to 19 million hogs and pigs on March 1, 2011. This estimate represents more than one-fourth of the nation’s estimated total. North Carolina (8.6 million) and Minnesota (7.6 million) were also homes to large numbers of pigs.

Number of Americans who said they have taken part in a barbecue during the previous year – 81 million. It’s probably safe to assume a lot of these events took place on Independence Day.