Example methods and apparatus for associating media devices with a demographic composition of a geographic area are disclosed. Disclosed example apparatus are to obtain a plurality of Internet Protocol addresses assigned to a media device associated with a panel member. Disclosed example apparatus are also to determine a most used Internet Protocol address from the plurality of Internet Protocol addresses, determine a geographic location corresponding to the most used Internet Protocol address, associate a geographic area with the media device in response to a determination that the geographic location corresponds to a location of an internet service provider, determine a demographic profile associated with the geographic area, and associate the demographic profile with the media device.