Google+, launched in late June, had 25 million unique visitors as of July 24 and is growing at a rate of roughly one million visitors a day, comScore noted in a presentation.
In contrast, it took Facebook about three years to attract 25 million visitors, while Twitter took just over 30 months, according to comScore.
While the data show Google's latest attempt at breaking into social networking has started strongly, it may not mean the project is a long-term success. MySpace grew to 25 million unique visitors in less than two years -- faster than Facebook or Twitter. However, it's lost a lot of visitors in the past year, comScore data show.
The United States had more than 6 million unique visitors, and India more than 3.6 million, the data show,
Canada and the UK had around 1 million unique visitors each, Germany over 920,000 and Brazil just over 780,000. France and Taiwan each had around 500,000.