Plastic baggies with locking, resealable zippers are manufactured and distributed by many companies. One of the most recognizable brand names that markets zippered plastic bags is Ziploc.
Ziploc brand zipper storage bags were introduced by Dow Chemical Company. According to Dow's website, the first Ziploc bags were test-marketed in 1968. This was the first time that the resealable bag was marketed as a way to keep food fresh. However, in 1954, a company called Minigrip, purchased the license to manufacture a resealable zipper bag. According to Minigrip's website, it manufactured the "first integral zipper plastic bag in the United States" in 1959. It wasn't until 1968 when the technology was licensed by Dow Chemical Company to be used for food storage.
Numerous websites, such as www.ziplock-bags.com, state that the zipper storage bag was patented on May 18, 1954, by Robert W. Vergobbi. However, U.S. Patent Number 2678768, which was issued to Vergobbi on May 18, 1954, is an invention called a "reinforced bag," which is sealed by applying heat or adhesive to the opening.
According to U.S. Patent and Trademark Office Records, Minigrip filed to trademark the word "Flextite" to describe "zippers and slide fasteners" on July 23, 1956, and "Plasti-Lip" to describe "plastic interlocking strip fasteners for use on clothing, bags and other articles" on Nov. 7, 1962. U.S. Patent and Trademark Office records also show that the Ziploc trademark was filed on Sept. 9, 1968, by Dow Chemical Co. and described as "plastic bags." While this is not indicative when or by whom the ziplock bag was invented, it does roughly confirm the dates reported on the websites of Dow and Minigrip. The original patent registrant of what we know today as the ziplock bag remains unconfirmed.
On Feb. 5, 1980, U.S. Patent Number 4186786 was issued to George F. Kirkpatrick with Union Carbide Corp. This invention was an "interlocking closure device" composed of two "closure profiles having different colors" that "can be easily identified visually in order to simplify the closing and opening of the container." In other words, this was a bag with a zipper that changed colors to show that it was closed. Union Carbide later became known as First Brands Corporation--owner of the Glad-Lock line--one of Ziploc's biggest competitors.
On Oct. 5, 1955, a company called Spotless Plastics Corp. registered "baggies" as a trademark. The trademark was later owned by Pactiv Corporation--the company that owns Hefty brand bags==another major competitor of Ziploc. On Nov. 26, 1991, F. John Herrington Jr. and Eric A. St. Phillips were issued the patent for a "plastic reclosable fastener with slider for opening and closing the reclosable fastener on plastic bags." About three years later on July 19, 1994, "Hefty One-Zip" was trademarked.