Back in August, Tyler Adams wanted to give a special shoutout to U.S. international teammate Weston McKennie for his birthday. He happened across a photo of the two of them when they were both in Bradenton, Florida, training with the U.S. under-17 national team.

"That photo came up and I just lost it," said Adams via telephone. "I thought it would be hilarious to post."

And with good reason. At the time, Adams was a good inch or two taller than McKennie, so he placed it side-by-side with a more recent shot, one in which the tables height-wise had definitely been turned.

"Wes hadn't hit his growth spurt yet, not even close to it," Adams said about the older photo. "Now he's six feet tall."

When Adams posted the photos to Twitter, they had their intended effect.

"It was definitely a shock because it was such a long time ago and you can see how far we've come," McKennie said.

The dynamic duo started way back. Happy birthday to my brotha! 🙌🏽❤️ Just getting started ✊🏽 @WMckennie pic.twitter.com/A4gfJgOIoe — Tyler Adams (@tyler_adams14) August 28, 2018

It's an understatement: the two boys have become grown men, and the growth hasn't been just physical. When the first photo was taken, Adams and McKennie were just a pair of young players whose potential was only outdone by their dreams. Now the two midfielders are on the cusp of becoming mainstays with the U.S. national team, part of a generation aiming to blunt the stigma from the team's failure to qualify for the 2018 World Cup.

There is a hope wrapped up in those photos that McKennie and Adams -- and the rest of their teammates as well -- can grow further and lead the U.S. to greater things.

The two are making considerable headway at club level. McKennie has been getting steady minutes with German club Schalke, both in the Champions League and the Bundesliga, while Adams is the heartbeat of a New York Red Bulls side pushing towards a Supporters Shield and MLS Cup double. On top of that, Adams is widely reported to be heading to RB Leipzig this winter. Along the way, McKennie and Adams have forged a friendship that carries onto the field, a bond that began with the U-17s.

McKennie, left, and Adams debuted for the U.S. senior side in the same match and after a strong year, the midfield pair are poised to lead this team through the next World Cup cycle and beyond. ESPN

The U-17 residency program in Bradenton, Fla. is now one that has now been consigned to history. Starting in 1999, the U.S. Soccer Federation would gather roughly 30 of the top youth players in the country with an eye towards forming the backbone of the U17 national team. But with the advent of MLS academies, as well as the USSF Development Academy, the residency program outlived its usefulness and the program ended in 2017.

Regardless, it's where the likes of Landon Donovan, DaMarcus Beasley, Jozy Altidore and Christian Pulisic spent some of their formative years; it gave up-and-coming players a taste of international soccer, as well as a glimpse of what life as a professional might look like, all while taking care of their schooling. It also included a competitive environment in which some players were away from home for the first time. That intensity can put a strain on relationships, but also form strong bonds.

"Residency isn't the easiest, because you're at a time period in your social life where you're missing out on high school and being back home, but you sacrifice that for being able to play soccer every day," Adams said.

"In my position, and for Weston as well, it was a big sacrifice. It's so enjoyable because you're around people that you like and who share the same passion as you. It was good to create such good friends because I feel like a lot of the kids that I went to residency with are still friends to this day. You form these good relationships."

Yet in the case of Adams and McKennie, it was one that took a while to germinate. Both players recalled the physical demands often didn't lend itself to much hangout time. Initially, Adams wasn't even a full-time participant in residency, jetting in for a week or two at a time before heading back to his home outside of New York City.

"We were more mutual friends but we were always cheering for each other," McKennie said. "Tyler was the more the chill, laid-back kid. We definitely had our fun times, our fun memories."

Adams, right, has been integral to the Red Bulls' playoff push and has made seven appearances for the U.S. since his 2017 debut. Rich Graessle/Icon Sportswire via Getty Images

That is the way of friendships, be it over the course of a life or even a few years. They ebb and flow; some even vanish. As one's job or city of residence changes, new relationships are formed and different roots are laid down. Interests can diverge and sever bonds thought to be unbreakable. Yet this was one connection that endured, even as Adams and McKennie took different paths towards becoming professionals.

When Adams' time with the U17s was up, he went back to the New York Red Bulls and began getting professional minutes with their reserve team. McKennie went back and played for FC Dallas' academy before signing with Schalke. Nick Taitague, McKennie's teammate at Schalke, proved to be the hub that kept the bond intact.

The friendship was given some added fuel last year when the pair was among those called in for the friendly against Portugal. The match proved to be the international debut for both players, with McKennie scoring the lone U.S. goal in a 1-1 draw. The fact that McKennie wasn't included in the U17 and U20 World Cup teams, of which Adams was a part, made their initial minutes at the senior level that much sweeter.

"It was just really cool, because we just had the same joy for each other," Adams said. "You've reached another milestone, and to see each other and how we've grown is definitely very special."

Their chemistry that was limited to time off the field now had more of an on-field component. Of the two, McKennie is the player with more of an attacking edge, though Adams has shown in recent months -- last Sunday's postseason triumph against the Columbus Crew in particular -- that he's making some headway in this regard.

There is a stylistic synergy as well.

McKennie has made 15 appearances for Schalke this season already, featuring in both the Bundesliga and Champions League. TF-Images/TF-Images via Getty Images

"I think we're both eager to press," McKennie said. "We both like pressing and we both have a good set of lungs -- we can definitely run for a while. I think that's one of the things we talk about when we do talk about going into games and game plans. We know we like to press, we know what kind of style we like to play. We're normally good together on the field. Whenever one guy goes up, the other has the other guy's back. I think we definitely compliment each other."

Adams added, "I feel like we're two very dynamic players and I think that's something that maybe the U.S. hasn't had in a long time. I think that having two midfielders like ourselves who can play and pivot off of each other is something that would definitely be unique going forward."

The upcoming friendlies against England (Thursday, ESPN2, 3 p.m. ET) and Italy will provide a measure of their progress, though the presence of Pulisic for just the second time this year will no doubt aid their respective causes.

But there is also optimism, and Adams' proposed move to Germany will offer the chance for a deeper connection, something beyond the group video chats now being held by not only McKennie and Adams, but also the likes of Taitague and Pulisic. Then there is the fact that after playing on the same team intermittently over the years, Adams and McKennie will find themselves being combatants instead of teammates.

"We're definitely tight now," said McKennie of Adams. "He's one of the few guys on the team that I've known since we were 14 years old -- Timothy Weah, too, and Pulisic. And with Tyler possibly making a move here, we'll probably have even more to talk about."

There will be more room for both players to grow as well.