Web sites operated by Target Corporation and Best Buy Company were among the four most-visited retail sites in the nation on Black Friday-and both companies experienced year-over-year increases in unique visitors.

According to ComScore, Inc., an Internet tracking firm, Minneapolis-based Target experienced a 9 percent increase in unique visitors over 2009, and Richfield-based Best Buy sites saw a 1 percent gain.

Those increases are indicative of the positive online trend that retailers across the country experienced during Thanksgiving week. Black Friday online sales totaled $648 million, up 9 percent from $595 million last year.

“Although Black Friday is known for the flurry of activity occurring in brick-and-mortar retail stores, online shopping is increasingly becoming the refuge of those preferring to avoid the crowds and long lines,” ComScore Chairman Gian Fulgoni said in a statement. “The $648 million in online spending this Black Friday represents the heaviest online spending day of the season to date…”

In addition to offering day-after-Thanksgiving deals, many U.S. retailers also offered both pre-Thanksgiving Day deals and Thanksgiving Day deals this year-and their efforts seemed to pay off, at least online.

Total online U.S. retail sales totaled $407 million on Thanksgiving Day, representing a whopping 28 percent increase over last year's holiday. Similarly, between November 1 and November 26, online retail sales nationwide totaled $11.6 billion-up 13 percent from the same period last year.

Amazon.com was the leading online retailer on Black Friday, according to ComScore; its number of unique visitors was up 25 percent from last year. Walmart joins Amazon.com, Target, and Best Buy on the list of the four most-visited retail Web sites this November 26.