Irving, Texas-based 7-Eleven Inc. is celebrating its 90th birthday on 7-Eleven Day (July 11).To celebrate its milestone birthday, 7-Eleven is inviting millions to enjoy a free Slurpee party, continuing the tradition that started on the retailer's 75th birthday in 2002.

Participating U.S. stores will give away an estimated 9 million free small Slurpee drinks from 11 a.m. to 7 p.m. local time, Tuesday, July 11, while supplies last. Slurpee fans can try the new Cotton Candy flavor or one of their favorites. The Cotton Candy flavor is all the goodness of the light, fluffy treat you loved as a kid in the form of a delicious Slurpee. New Cotton Candy Slurpee flavor is only available for a limited time at participating stores.

Slurpee Week continues the summer celebration; consumers who purchase seven Slurpee drinks between July 12 and18 and scan the 7-Eleven mobile app will receive 11 free Slurpee drinks, the company says. New this year, Slurpee cup icons will appear in the app, showing customers' progress toward the 11-free goal. Slurpee purchases also will count toward the ongoing Buy 6-Get 7th Free 7Rewards offer.

Once seven Slurpee drinks are purchased, 11 free Slurpee coupons automatically will appear in the "Scan and Save" section of the 7-Eleven mobile app 24 hours after the qualifying drink purchase. The 11 free Slurpee drink coupons can be redeemed one at a time or all at once. The deadline to enjoy all 11 free Slurpee drinks is Aug. 31.

"Celebrating our birthday with a free Slurpee drink, the product that is probably most closely associated with 7-Eleven, is a natural and fun way to mark the day," said Laura Gordon, vice president of marketing and brand innovation at 7-Eleven, in a statement. "7-Eleven Day is a celebration, not only of our birthday, but more importantly, of our customers. Ninety years is a big birthday, and our customers are the ones who got us here. By adding Slurpee Week, we have a whole week to say thank-you for their business throughout the year."

During the annual birthday bash, 7-Eleven will offer a sneak peek at its new Slurpee cup design with colorful bubbles and swirls. The small cups for free Slurpee drinks will feature the new design. Other sizes will launch later, it says.

A new Ultimate Slurp Straw that is more than twice as big as a regular straw will make the small Slurpee go down even faster and supports a Brainfreeze waiting to happen. The suggested retail  is price $0.99.

Other size Slurpee drinks will be available for purchase including the shiny, selfie-inducing chrome dome and cup, it adds.

Every year, July 11 marks the day that the world's No. 1 convenience retailer observes its birthday and other company milestones. 7-Eleven introduced its iconic frozen carbonated beverage in 1966, and it was an immediate hit, the company says. The next year, the company's advertising director coined the word "Slurpee" to describe the sound the drink made traveling through the straw. And a star was born, it adds.

Wacky flavor names and quirky radio spots created a drink craze among teens and young adults, the same demographic group that today makes up the drink's biggest fans. Slurpee drinks enjoy worldwide popularity, with more than 7.4 billion Slurpee drinks slurped during its colorful history, enough for everyone on earth to enjoy one, the company says.

7-Eleven, the first convenience store, began its run in 1927 when a Southland Ice Co. employee began selling bread, milk and eggs on an ice dock in a Dallas suburb. Since that inauspicious start, "convenience" has become a big business. The small ice company has grown into a major international retailing chain with almost 11,000 7-Eleven stores in North America and more than 62,000 stores worldwide, it says.

The 7-Eleven mobile app is available via the App Store or Google Play. After downloading, customers can then register to become a 7Rewards member and take advantage of Slurpee Week.