Examples to determine media impressions using distributed demographic information are disclosed. An example apparatus includes a reporter to detect at the client device a login event. The example apparatus also includes a communication interface to send a communication to an impression monitor system in response to the reporter detecting at the client device the login event via the login webpage, the login event associated with a first Internet domain different from a second internet domain of the impression monitor system. The example communication interface also sends a login reporting message to the database proprietor, the login reporting message including first and second cookie identifiers, the first cookie identifier associated with the first Internet domain, and the second cookie identifier associated with the second Internet domain of the impression monitor system.