Paul Arriola had his first workout with D.C. United on Thursday. (Marvin Joseph/The Washington Post)

For four years, Paul Arriola had perhaps the most unusual commute in pro sports. Each work day, he would leave home in suburban San Diego and pass through the world’s busiest land border crossing to report to his Mexican pro soccer team, Club Tijuana.

Russell Canouse, Arriola’s friend from youth national team camps, left Pennsylvania Dutch Country at age 15 and relocated to a village of 3,200 in southwestern Germany to launch his soccer career.

Both chased dreams abroad, where soccer‘s development, infrastructure and, in many cases, financial reward are decades ahead of their home country. But as the sport has blossomed here, some young Americans with global ambitions are taking a second look at MLS.

For Arriola and Canouse, the time and opportunity to return arrived this summer. And on Saturday night, at the end of a whirlwind week for two 22-year-old midfielders and a sputtering team, they’ll suit up for D.C. United against Real Salt Lake at RFK Stadium.

They were among D.C.’s four signings before MLS’s trade and transfer window closed Wednesday. Bolivian forward Bruno Miranda and Hungary midfielder Zoltan Stieber were the others. All are available this weekend, except Stieber, whose work visa is pending.

As part of the roster makeover, which will carry into the winter, United targeted youthful U.S. candidates outside MLS. But would they consider returning home? Despite the league’s growth, there is a lingering perception — some would call it reality — that MLS is far inferior to many traditional pro circuits.

In Arriola’s case, MLS is slowly gaining on the Mexico’s top division, known as Liga MX, and with an opportunity to more than double his salary (to an estimated $1 million) and become a centerpiece in United’s new stadium starting next summer, he spurned European interest.

“The plan D.C. had for me was what I was looking for,” Arriola said. “That made it easy. I’m American. Ever since I’ve been watching soccer, I’ve been following MLS. The more it’s grown, the more I’ve watched it. The interest to play in MLS has always been there. Four years ago wasn’t the right time for me. I knew one day I wanted to come back.”

Before joining Tijuana, Arriola weighed an offer from the Los Angeles Galaxy, which had him in its youth academy for a year. However, without first-team readiness, he wouldn’t have received much practical experience playing for the Galaxy reserves.

Since then, MLS teams have bolstered their development programs and entered teams in, or forged partnerships with, the second-division United Soccer League.

There was another factor in Arriola’s move to MLS.

“In the end, look, you have to do what makes you happy,” he said. “A lot of people forget that. Soccer players, we’re all humans. The only thing we can ask for as humans is to search for happiness. This was a spot I felt comfortable with and I knew that coming here I would be happy.”

He wasn’t necessarily unhappy at Tijuana, where he started 37 times across all competitions the past two years. “But I knew if I wanted to continue to grow,” he added, “I had to leave.”

United paid Tijuana a transfer fee of more than $3 million, more than twice the club record.

Some soccer fans believe Arriola’s move to a last-place team in an inferior league will hinder his development and affect his form with the U.S. national team. After starting two World Cup qualifiers and excelling in the CONCACAF Gold Cup, Arriola is well positioned for a berth on the World Cup squad next summer.

However, with the MLS playoffs almost out of reach this fall, Arriola is staring at inactivity from late October until U.S. camp in January — an eternity in the soccer world.

Before accepting United’s offer, Arriola conferred with U.S. Coach Bruce Arena.

“It’s a good move,” Arena said in a phone interview Thursday. “It’s not perfect because the year’s a little short, but the world doesn’t revolve around me or the national team. You’ve got to do what’s best for you. Ben Olsen will do a good job with him.”

Arriola is among several U.S. teammates from foreign leagues to join MLS teams in recent years. The list includes Michael Bradley, Clint Dempsey, Jozy Altidore, Tim Howard and Brad Guzan. Arriola, who made his U.S. senior debut 15 months ago, is by far the youngest of the bunch.

“Sooner rather than later, kids aren’t going to want to go other places to get more games and improve their quality,” Arriola said. “There will be nothing better than to be able to stay in the United States and continue to grow and be confident that you are getting the best out of yourself and the situation.”

Canouse’s situation was different. He had been under contract with Hoffenheim in Germany’s elite Bundesliga but on loan to Bochum in the second flight for more than a year. Last season, he made 20 league appearances and scored once.

His only first-team appearance with Hoffenheim came in March 2016. He could’ve stuck it out longer, hoping to be recalled to his first club or gaining promotion with Bochum to the Bundesliga. But with interest from MLS, the time was right to move.

“I liked what D.C. proposed: the new stadium, the group of guys, my development,” said Canouse, a former New York Red Bulls’ academy player who, unlike Arriola, didn’t received a homegrown contract offer. “I could see myself playing here and being part of something special.”

There was an emotional tug, as well. Before Philadelphia was awarded an MLS team, Canouse traveled with his father from Lancaster, Pa., to attend multiple United matches each summer. He remembered watching Olsen, Freddy Adu and Alecko Eskandarian, and seeing an MLS all-star game at RFK. Olsen, a central Pennsylvania native, once spoke at a soccer camp he attended.

Canouse said his MLS contract is “comparable” to the Hoffenheim pact. United did not have to pay a transfer fee.

“It was very difficult leaving Germany,” he said. “I grew up there. It definitely became part of me. It was my second home. But I told them I really wanted to do this.

“MLS has come a long way. I am hoping to come in and be a part of the growth. As a kid, it was a goal of mine. It’s nice to be part of it now.”

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D.C. United vs. Real Salt Lake

Where: RFK Stadium.

When: Saturday at 7 p.m. ET.

TV: NewsChannel 8.

Records: D.C. 5-14-4, 19 points; Real 7-12-5, 26 points.

D.C. probable starters: GK Bill Hamid; Ds Sean Franklin, Steve Birnbaum, Kofi Opare, Chris Korb; MFs Paul Arriola, Marcelo Sarvas, Jared Jeffrey, Luciano Acosta, Nick DeLeon; F Deshorn Brown.

RSL probable starters: GK Nick Rimando; Ds Tony Beltran, Marcelo Silva, Justen Glad, Chris Wingert; MFs Jefferson Savarino, Kyle Beckerman, Sunny, Albert Rusnak, Joao Plata; F Luis Silva.

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