The 19-year-old from Millersville, MO, gunned into the lead from the front row outside and led all 30 rounds to become the fourth different winner of the event, adding his name to the list of past 600 Nationals championship that includes Travis Senter, Jr. (twice), Jerrod Wilson and Jason Lair.
Miller and Pennsylvania's Brock Zearfoss battled for the point much of the way in Saturday's finale before another Keystone State rep, Michael Dicely, moved by Zearfoss into second in the closing rounds. Dicely closed the gap on Miller but ran out of laps, with Miller taking the checkered flag just 0.214-seconds ahead of Dicely.
Zearfoss settled for the show position, with Kansas contender Nate Fleming climbing from the sixth row to fourth by race's end. After advancing from "B" Main action, Travis Senter, Jr., charged from 18th to round out the top five.
Christopher Bell was sixth, with 20th-starter Tyson Hall, Ryan Greth, Scott Sawyer and 17th-starter Tyler DeVault completing the top ten.