Young had the most points by any player making his conference finals debut since the NBA adopted the conference format 50 years ago.
The best-of-seven series continues Friday at Milwaukee with the winner advancing to an NBA Finals matchup against either the Phoenix Suns or the Los Angeles Clippers.
John Collins scored 23 points and grabbed 15 rebounds while Clint Capela had 12 points and 19 rebounds.
“People overlook this team, take us for granted, so for us to come out here and get a win is big time,” Collins said.
Greek star big man Giannis Antetokounmpo had 34 points, 12 rebounds and nine assists while Jrue Holiday had 33 points and 10 assists for the Bucks in a losing cause.
Khris Middleton, who went 0-of-9 from 3-point range, missed an attempt to lift the Bucks level from beyond the arc in the final seconds to seal Atlanta’s victory.
“I believe in this team,” Young said. “We knew we could get a stop. We just buckled down and got it.
“Our confidence never goes away. We put too much work in to stop believing in each other.”
There more than 16,000 spectators in the Bucks’ arena and about as many outside watching on a huge screen.
The Hawks, who had lost their seven prior games in Milwaukee since 2016, were based in Milwaukee for four seasons in the 1950s. They won their only NBA title in 1958 while based in St. Louis. They last reached the NBA Finals in 1961 when based in St. Louis.
The Bucks lost to Toronto in the 2019 conference finals and to Miami in last year’s conference semi-finals, with Antetokounmpo winning the NBA Most Valuable Player award both seasons.