Leading the way was teenage athletes Britt Cox and Nicole Parks, who both recorded victories, with Cox also winning a bronze medal.
NSWIS Head Coach Peter "Toppa" Topalovic was extremely happy with the girl's performance.
"The team has had a great training camp in Apex, Canada, which gave them a strong lead-in to the US Selection events".
"The result will give both girls confidence for the season and best of all they both are capable of further improvement in their competition runs and can lift their performance even further".
Brodie Summers was the leading male skier for Australia in 23rd place, with NSWIS team-mates Sam Hall and David Graham in 27th and 30th place respectively.
The US Selection events are very competitive, with America's best skiers battling it out for a chance to compete on the World Cup tour for the strong US team.
Two more events will take place in Steamboat, with a singles and dual mogul event scheduled for later this week.