Aaronson was born and raised in Medford, New Jersey and the midfielder's early exploits led to the American being labelled the 'Medford Messi'.
The Whites recruit initially came through the Philadelphia Union Academy and then moved to Bethlehem Steel, making 21 outings during the 2017 and 2018 United Soccer League Championship campaigns, American football's second tier.
Aaronson enjoyed a particularly strong end to the 2018 season and signed for Philadelphia Union for the 2019 MLS season which meant the step up to the top tier of the MLS.
Then just 18 years old, the midfielder took to the step up in class in his stride and established himself as a dependable starter in both the no 8 and 10 roles.
Thirty-six outings including four goals and one assist followed and Aaronson took a further step forward the following year, the start of which presented his international debut for the USA.
The midfielder weighed in with four goals and three assists as part of 20 outings in the MLS season in which he was named in the league's best XI of the year.
The Philadelphia star also excelled in the MLS Is Back Tournament at the end of the year in which he added two more assists.
With Aaronson now also gaining more minutes for the US national team, an RB Salzburg side managed by Jesse Marsch then came knocking fir his talents.
The Austrians paid a reported fee of $6m to snap up his services, the move taking effect from January 2021 after the 2020 MLS campaign had ended.
Aaronson made his Salzburg debut as a second-half substitute in the 2-0 league win at SCR Altach on January 24, 2021.
By the end of the next month, the midfielder had two Europa League outings under his belt as his side were beaten over two legs by Villarreal.
Despite only joining in January, Aaronson clocked up 25 appearances, seven goals and five assists as Marsch's side stormed to a domestic league and cup double, Aaronson scoring in the cup final victory against LASK.
Boss Marsch then moved to RB Leipzig that summer but Aaronson stayed put and enjoyed another very fruitful 2021-22 campaign in which his side overcame Brondby to qualify for the Champions League group stages.
Aaronson scored in both legs of the final qualifying round play-off against Brondby, as well as contributing an assist, and Salzburg then made it all the way to the last 16 o f the competition in which they were eventually knocked out by Bayern Munich.
But the Austrian's held Bayern to a 1-1 draw in the first leg at the Red Bull Arena in which Aaronson set up Junior Adamu to put his sides in front. Another assist followed in the second leg in Munich in which Salzburg were hammered 7-1.
All told, Aaronson bagged ten Champions League outings including nine starts during the 2021-22 campaign and domestically Salzburg recorded yet another league and cup double, finishing 18 points clear of Sturm Graz.
Aaronson chipped in with another four goals and five assists during the league campaign and he leaves Salzburg having made 65 appearances which featured 13 goals and 15 assists.
The midfielder has also earned 18 caps for the USA since making his debut in February 2020, scoring five times for a side who will be in England's group at the 2022 Qatar World Cup.
Aaronson, though, is now part of Leeds United's group: Welcome to Elland Road the Medford Messi.