Yahoo Sites again edged Google Sites out among US web properties (138 million visitors vs. nearly 135 million) as traffic to the tax, politics, career, real estate and travel sites increased, according to a monthly analysis by comScore's Media Metrix, reports MarketingCharts.

Among the December data released by comScore:

Top 50 Properties (Unique Visitors)

Among the highlights:

• Third after Yahoo Sites and Google Sites was Microsoft Sites with 119 million visitors.
• During the month, large increases were experienced by the following properties; Superpages.com Network (rising 13 spots to position 19), Disney Online (up four spots to position 22), and Expedia Inc. (up nine spots to 32).
• CareerBuilder LLC entered the ranking this month grabbing position 27.

Beginning with January comScore Media Metrix data, Time Warner Network has been divided into AOL LLC, which includes all AOL-related entities, and Time Warner - excluding AOL.

Top 50 Ad Focus Ranking (Advertising Reach)

Among the highlights:

• Platform A, the ad network combining Advertising.com, Tacoda, AOL, and Quigo, debuted this month in the top spot in the Ad Focus Ranking, reaching 91 percent of the more than 184 million Americans online.
• Substantial gains were achieved by Adconion Media Group (up four spots to 14), PrecisionClick (up six spots to 35), and Kontera (up four spots to 36).
• Three entities joined the ranking this month: Turn, Inc., IACAS Network, and CNN.

For coverage of high-growth sites and categories, including additional tables, see MarketingCharts.