In a display highlighted by brute force and savage power in the first 50 and a more watchful approach in the second, the Barbados captain lashed an unbeaten 104 off 127 balls and a target of 159 in 50 overs was easily wiped off by himself and Sherwin Campbell in the 37th over by 3:45 p.m.
Campbell finished the match with a trademark cut that carried him to his fifty off 89 balls.
The 10-wicket win, if not an as entirely rewarding as the one against the Leeward Islands when the fielding was of a much higher standard, virtually confirmed their place in next weekend's Red Stripe Bowl semifinals.
A day after his 62 off 57 balls against the Leewards, the 28-year-old Wallace reeled off a wider variety of strokes. On Thursday, he was fed a diet of short bowling which was repeatedly pulled away, but yesterday, did a lot more driving, cutting and flicking in getting his 10 fours and a six.
The tall opener arrived at his half-century by flicking the medium-pace of Abdul Islam Nazir for a huge six over square-leg that prompted excited schoolchildren to chase after the ball.
Wallace's chanceless 100, his first in his 37th regional one-day match since his debut in 1990, surpassed his previous best of 87 against Bermuda at Enmore in Guyana two seasons ago.
He was somewhat modest over his exploits over the last two days. Instead, he heaped a lot of praise on Campbell with whom he added 89 against the Leewards.
``Sherwin and myself batted really well. We ran between the wickets well. We're growing as a very good opening pair and I hope we can continue to grow in the vein that Desmond Haynes and Gordon Greenidge carried the Barbados flag for a long time,'' he said.
Wallace signalled his intentions by lifting Richard Louis, the former Barbados Olympic quarter-miler, back over his head and followed up by hoisting him through mid-wicket off the next ball.
Campbell, outscored but not outdone, was the perfect anchor and his most memorable stroke was a pulled six off the front foot against medium-pacer Nazir.
The United States, the new kids on the block, enjoyed their best batting performance of the tournament, but their 158 for nine, was never going to seriously challenge Barbados.
On another blisteringly hot day at the lovely Alpart ground, the tournament debutants survived the opening exchanges on a pitch that contained plenty moisture to surpass their all out totals of 88 and 107 in their two previousmatches.
Winston Reid sent his customary tight spell, his 10 overs going for 22 and Barbados' other impressive bowlers were the teenagers Ryan Hinds and Antonio Mayers.
Hinds, bowling straight, flat left-arm spin, had 13 runs from the first five overs and when the United States tried to get after him, he collected three wickets in four balls.
Mayers, one of three changes in the line-up, delivered his medium-pace on the perfect line and length and the batsmen could only score one run from his first four overs.
The American effort was built around a solid half-century from left-handed opener Rohan Alexander and the support he received from fellow Jamaican Dave Hoilette in the middle.
Alexander, missed at 19 and 24, looked an accomplished player in making 55 off 120 balls, but the United States were never able to dominate the bowling.