Websites for the U.S. House of Representatives, U.S. Senate and state legislative bodies contain roll call votes of individual bills, amendments and resolutions as public information, as of 2015. The Congressional Record is also on iTunes and in libraries. The exact method varies by institution and date of the legislation.
Most federal government institutions offer searches by bill number, year or session. State legislative websites differ on necessary information to locate votes on legislation. For example, the Texas House of Representatives requires a search using the bill number. The Minnesota House of Representatives organizes vote data by session and then date or bill number.