The Americans netted six second-half goals -- two of them in the first five minutes of the half -- to pull away after Scotland, dominated throughout the first 45 minutes, managed to stay even until halftime.
Hamm, coming off a sensational second half of the season with WUSA runner-up Washington, scored in the 35th, 50th and 68th minutes and created goals by Wambach in the 64th and 89th and Shannon MacMillan in the 78th.
Coach April Heinrichs gave all 18 of her players time in the match, and Lorrie Fair -- earning her 100th cap -- served as captain. A moment of silence was held before the match in honor of Lark Chastain, Brandi Chastain's mother, who died on Friday. The U.S. team wore yellow arm bands in her memory, and Chastain played the full 90 minutes in central defense.
Heinrichs continued to work with a 4-4-2 formation as she readies the team for the Oct. 28-Nov. 9 CONCACAF Women's Gold Cup, which will double as the region's qualifying tournament for next year's Women's World Cup in China. U.S. preparations will continue in the U.S. Women's Cup, with matches against Russia (Sept. 29) in Uniondale, N.Y., and Australia (Oct. 2) and Italy (Oct. 6) in Cary, N.C.
''We wanted to stay true to our week, and our week was about developing individuals and our system that we are working with,'' Heinrichs said. ''We could have made several changes at halftime, maybe go with a three-front or play high-pressure, which is our traditional way of playing, and maybe that wins that game for us. But we stayed with the 4-4-2, stayed in a low-pressure style and said, 'Let's develop this system.' ''
The Yanks jumped ahead on Cindy Parlow's 12th-minute near-post strike from a nifty Kristine Lilly feed, and they might have scored another four or five in the first half with better fortune. Defensively, the Americans struggled, and Julie Fleeting and Debbie McWhinnie answered U.S. goals to keep the Scots level, 2-2.
Fleeting, who scored three goals with San Diego in the WUSA after arriving late in the season, knocked home a rebound in the 34th minute after U.S. goalkeeper Hope Solo, on leave from the University of Washington, dived to stop a Joanne Love shot.
Hamm got her first seconds later, beating a defender to Lilly's cross from the left and redirecting it off goalkeeper Gemma Fay. Scotland again pulled even a minute later, with Fleeting catching Solo out of position and McWhinnie beating Kate Sobrero to the cross.
The Scots might have been up, 3-2, at halftime -- Fleeting missed to the right by about a foot in first-half stoppage time.
It was over early in the second half as Wambach, who came on for Parlow at halftime, and Hamm tore Scotland's defense apart.
''It was a great start for us, but the second half showed the difference between the two countries,'' Fleeting noted. ''I think we were real beat, as you could tell at the end. The [90-plus-degree] heat is definitely different from what we are used to, and we struggled with that a bit, and our tired legs took its toll.''
Wambach scored 112 seconds into the second half, heading home a Jenny Benson cross after playing the wing-defender down the left flank. Hamm scored her second in the 50th after picking off a poor back pass from Shelly Kerr.
Wambach made it 5-2, volleying in a nice pass from Hamm in the 64th minute, and Hamm had her hat trick four minutes later from a Wambach feed. Another fine pass from Hamm set up MacMillan 10 minutes later, and she fed Wambach for a header in the final minutes.
Wambach, who had scored one international goal heading into the match, injured her ankle on her third goal and departed the match. Because Heinrichs had already spent her bench, the Americans played with 10 women for a brief stoppage time.
Hamm's hat trick was the 10th of her international career, and it left her with 133 goals in 221 international matches.
Sept. 8 at Columbus, Ohio
United States 8 Scotland 2. Goals: Parlow 12, Hamm 35, 50, 68, Wambach 47, 64, 89, MacMillan 78; Fleeting 34, McWhinnie 36.
United States -- Solo (Scurry, 46); Sobrero (Mitts, 64), Bryan (Lindsey, 46), Chastain, Benson; Roberts (Kluegel, 62), Fair, Lilly (Hucles, 46), Foudy (MacMillan, 64); Parlow (Wambach, 46), Hamm.
Scotland --Fay (Johnstone, 76); Kerr (Robertson, 84), Cook, Grant, Barr; Smith (Sneddon, 65), Love (Annand, 73), Gilmour (Bruce, 88), James; Fleeting (Grant, 76), McWhinnie.
Yellow cards --Scotland: Cook 37.
Referee -- Rachel Woo (U.S.). A -- 6,295.