Tracking firm NPD Group reported that 98,500 PS3s were sold, compared to 198,400 Xbox 360s (up 28%) and 381,800 Wiis (up 13%).
Sony said that the $100 (£50) price cut to the 60GB PS3 led to a 135% sales rise over the last two weeks.
Independent figures for sales of the cheaper PS3 are not yet available.
"This jump in sales bodes very well for us heading into the fall as we launch an impressive arsenal of hardware and software," Jack Tretton, head of Sony Computer Entertainment America, said in a statement.
Nintendo's DS handheld sold 561,900 units , while Sony's PSP, which has been boosted by an April price cut, sold 230,100 units, NPD reported.
Software sales in the US are 31% higher than the same time last year, the market research showed, buoyed by new consoles from all three firms.
Last month's sales topped $1.1bn (£550m), the data revealed.
"The industry continues to realise substantial gains, month after month, and on all fronts it's great growth," NPD analyst Anita Frazier told Reuters news agency.
Nintendo said the sales showed that the firm was reaching a new gaming audience.
"We are delivering on our message of reaching out to new gamers," said Nintendo spokeswoman Beth Llewellyn.