Queenslander Simon Nash was the other to win the event when he was successful in 2002 while attending University in the US.
Drakeford has continued a good week for Australian golf in amateur events in the USA.
Last Sunday Ryan Ruffels and Karl Vilips won their respective Callaway Junior World Junior Championship in San Diego and this week Curtis Luck and NSW's Shelley Shin reached the semi-finals of their respective US Junior Championships.
For Drakeford also it follows on from a 6th place finish at the Players Am Championship and a runner-up finish at last week's Southern Amateur Championship.
Drakeford took a three shot lead into Saturday's final round and appeared to be well in control until a double bogey at his 12th hole opened the door for his chasers.
Hossler and McCarthy closed strongly but despite a bogey at the last Drakeford had done enough to see it through.
Victorian Ben Eccles finished 4th and NSW's Dale Brandt Edwards finished 9th.
The next significant amateur event on the US summer schedule is the time honoured Western Amateur at the Beverly Country Club in Chicago where many of the Australians who teed it up this week will participate.