This year marks the 20th anniversary of the arrival of Ken Griffey Jr. to the big leagues. Just 18 years old when he stepped onto the field with the Seattle Mariners to open the 1989 season, it didn't take long for "Junior" to have an immediate impact on the game.

And it didn't take long for Griffey to have an immediate impact on another part of the baseball world, either. His debut in a Mariners uniform coincided with the debut of a new baseball card maker, Upper Deck, which made Griffey's rookie card No. 1 in its first-ever card set. The result was one of the most popular cards in the modern baseball card era.

There had been plenty of anticipation surrounding Griffey's debut with the Mariners. He was the team's No. 1 Draft pick in 1987, the son of Ken Griffey, who was a member the powerful Cincinnati Reds teams that won two World Series titles in the 1970s. In addition to his well-known father, Junior shares a birthday with Stan Musial (Nov. 21) and wore No. 24 to honor Willie Mays. Everything about him suggested greatness.

The Mariners, who had never had a winning season since joining the American League in 1977, hoped Griffey could be the player to help turn around the fortunes of the franchise. His arrival in Seattle came even earlier than the front office anticipated. After only a year and a half in the minors, Junior was the Mariners' starting center fielder on Opening Day of the 1989 season. He doubled in his first at-bat and homered on the first pitch he saw while playing in Seattle's Kingdome. He instantly became the most talked-about rookie in baseball.

Upper Deck's arrival on the baseball card scene was a little more under the radar. The company had produced some promotional cards to hype its first set and handed them out at card shows. The cards definitely looked nice, but there were already five other companies licensed to make baseball cards in 1989. And Upper Deck's suggested retail price was 89 cents per pack, by far the highest of any products available at the time. Some veteran collectors snickered, saying nobody would ever spend that much on a pack of baseball cards and that the market wouldn't support a sixth baseball card maker.

But Upper Deck executives had plans to make the company's cards stand out from the crowd. The cards featured an anti-counterfeit hologram sticker, designed to give collectors assurance the cards were not worthless copies, and were sold in tamper-proof foil packs (both industry firsts). The cards were produced on a brilliant white card stock, had crisp color photos on both sides (most companies only had photos on the fronts) and were produced in lower quantities than any of Upper Deck's competitors.

Company officials also knew that in addition to nice looking cards, they needed to have plenty of up-and-coming prospects in the set to attract the attention of rookie-card collectors -- those hobbyists who bought up large quantities of virtually every highly touted youngster in the hopes that the cards purchased for entry-level prices at the start of their careers would turn into blue-chip investments once that player became a superstar.

There was no shortage of talented rookies scheduled for the 1989 Upper Deck set. Players like Chris Sabo, Randy Johnson and Sandy Alomar Jr. already had attracted the attention of collectors. Griffey wasn't even on the Mariners' 40-man roster when spring training began in 1989.

Tom Geideman, one of Upper Deck's first employees and the man who helped determine which prospects were deserving of being included in the set, suspected Griffey wouldn't be in the Minors very long. Not only did he want Griffey in the set, he wanted him to be card No. 1 in the set. In most cases, the choice of what player is pictured on card No. 1 in a set had no real relevance other than somebody had to occupy that space. But Geideman, just 18 years old at the time, believed the selection had more relevance in the company's very first release.

There was one problem. Upper Deck didn't have a picture of Griffey in a Mariners uniform. The best image available was a photo of the young prospect holding a bat on his shoulder and wearing the black hat of his Class-A club, the San Bernardino Spirit.

So company officials used their photo touch-up skills to make it appear as if Griffey was wearing a Mariners cap, and arguably the most famous baseball card of the decade was created.

How realistic did the photo look? Griffey reportedly asked an Upper Deck photographer the following year when the photo of him wearing a Seattle hat had been taken, because he couldn't ever remember posing for it. The photographer had to explain to him how it was created.

The text on the back of the card featured a prediction that has since proven to be accurate. "Ken Jr. is ... possibly the finest young talent the Mariners have ever produced," the card states.

Production problems resulted in the 1989 Upper Deck Baseball set arriving three months later than planned, but the product was an immediate hit with collectors. The cards themselves had a premium look and feel to them, and the pack prices soon soared to more than $1.50 on the secondary market -- chump change today, but a never-before-seen price point in that era.

The Griffey rookie card played a big part in the product's popularity, in part because of his play on the field, and in part because none of the other card companies had included him in their initial 1989 releases. By the end of the 1989 season, the card was selling for $10. A year later, it had moved to $30. By the end of 1991, it doubled to $60. By the time Griffey completed his first decade in the big leagues, he had chalked up nearly 400 home runs, won 10 Gold Gloves and was a 10-time All-Star. His rookie card was priced at $130.

Today, Griffey is again playing for Seattle, and is one of just six players to ever hit more than 600 career home runs. He's almost certain to be a first-ballot Hall of Famer. Many experts believe that had he not been hampered by injuries after he left Seattle and joined the Cincinnati Reds, he may have been the first to surpass Hank Aaron's mark of 755 career home runs.

So why is his rookie card worth a mere $40 today? It's largely because of the speculative nature of the card market during the 1990s. While always popular, the card just wasn't as scarce as some had first believed, and the supply (an estimated 1.5 million copies of the card) was more than enough to meet the demand. Today, the card is valued at around $40 -- a disappointing price if you bought the card at its peak but a fairly lofty price compared to just about any other card produced in that era. However, some versions of the card that have been submitted to the top grading services and received "gem mint" grades can still command up to $300.

Twenty years after its debut, the significance of the Griffey rookie card is about more than its monetary value. It has not only proven to be one of the most collectible rookie cards of the last 20 years, but its popularity arguably surpasses that of any rookie card issued since Nolan Ryan's 1968 Topps debut. There have been many rookie cards released since the 1989 UD Griffey card that are more scarce and more valuable, but none have created the same kind of buzz across the hobby, and none represent the simultaneous arrival of a future Hall of Famer and a cardmaker that has had a lasting impact on the baseball card industry.

Not surprisingly, Upper Deck is using the popularity of the Griffey card as one of the focal points of its 20th anniversary product line this season. The company went to the secondary market and purchased 89 copies of Griffey's rookie card and had him autograph the cards, which were then randomly inserted in packs of Upper Deck Series One Baseball. Meanwhile, card No. 801 in Upper Deck Series Two Baseball features a "What If...?" theme, as in "What if Ken Griffey Jr.'s rookie card had featured an action shot instead of a posed photo?" The card features the 1989 card design and a picture of him at the plate during his rookie season.

"Ken Griffey Jr. has meant so much to the Upper Deck Company over the last two decades," said Jason Masherah, Upper Deck's senior sports brand manager. "His rookie card basically put us on the map 20 years ago."