A total of 128,575 fans have turned up to see United's opening two games against New England Revolution and the Seattle Sounders. But City managed to get only 35,325 through the gates for their clashes with Club America and the Canadian side Vancouver Whitecaps.
Sir Alex Ferguson's men have also received greater coverage in the US media.
The Wall Street Journal has documented United's tour since they've arrived, but have been quiet on Roberto Mancini's men.
Tom Cannon, professor of strategic development at Liverpool University, told the Manchester Evening News: "United have undoubtedly made a bigger impact in America. They've been working there a lot longer as they have in most areas.
"City are making a lot more effort now though. The influence of Beckham has made United a massive brand in America.
"America is the only big gap left in the global football market, every other part of the world has been developed.
"United are still the biggest global brand, but City aren't that far behind. America gives the clubs a great opportunity to expand their brand.
"Most people assume football will take off in North America at some point, it's the next big source of talent. If owners are global players like the Glazers and the Mansour family, North America is vital"