Got curious about how the different traffic rating services ranked the top 10 websites in the United States last month.

Here’s what I found:

Alexa:
1. Yahoo!
2. Google
3. Myspace
4. Youtube
5. Facebook
6. MSN
7. Ebay
8. Windows Live
9. Wikipedia
10. Craigslist

Quantcast:
1. Yahoo!
2. Google
3. AOL
4. MSN
5. Myspace
6. Ebay
7. Mapquest
8. Microsoft
9. Windows Live
10. Amazon

Nielsen NetRatings:
1. Google
2. Yahoo!
3. Microsoft
4. MSN/Windows Live
5. AOL
6. Fox Interactive Media (Myspace, Photobucket)
7. Ebay
8. Youtube
9. Wikipedia
10. Amazon

comScore:
1. Yahoo! Sites (Geocities, Mybloglog, Flickr)
2. Google Sites (Youtube, Blogger)
3. Time Warner Network (CNN, AOL, Mapquest)
4. Microsoft Sites (MSN, Live)
5. Fox Interactive Media (Myspace, Photobucket)
6. Ebay
7. Amazon
8. Ask
9. Wikipedia
10. Viacom Digital (MTV, CBS, Nickelodeon)

Yahoo!, save for Nielsen’s list, is the most popular website in the USA, or do I dare say the whole world? That can be largely attributed to their ubiquitous email service, Yahoo! Mail. However, Google is, hands down, the most widely used search engine, commanding a 53.6% market share. Yahoo!’s search pales in comparison, capturing only 19.9% of the market. Interestingly, in July this year, Nielsen reported that 63% of those who used Google also searched in Yahoo! and MSN. This phenomenon is called an “overlap”. Notably, MSN had the highest overlap rate of 84%. This shows that users are not always satisfied with the search results they see, thus they check other search engines.

Seven websites or online properties were consistenly in the top 10. They are Yahoo!, Google, MSN, Myspace, Ebay, Windows Live and Wikipedia. Amazon didn’t make the list due to its 11th ranking with Alexa. I am doubting if Craigslist receives enough traffic to merit a place in a top 10 list as it ranks only 23rd and 28th in Quantcast and comScore respectively.