Altoona is a city in Eau Claire County, Wisconsin, United States. The population was 6,706 at the 2010 census. The city is a railroad terminal on the Union Pacific Railroad. Continued growth in both Altoona and Eau Claire over the past century has left the two cities adjacent to one another, with Fairfax St. and Bus. 53 providing a general boundary between the two, although the actual border is irregular. Altoona is bounded on the north by Lake Altoona and the Eau Claire River. To the south, the city limits generally follow U.S. Highway 12 and Otter Creek.