Attendance from Baseballreference.com. I count "MLB" to be the National Association (1871-1875)/National League (1876-1902) prior to 1903. In that year, historians tend to agree that the National League and the American League (begun in 1901) reached business peace and 1903 also is the first World Series between the NL and AL. Unfortunately, I have only been able to find attendance data beginning for the NL in 1890. For all other leagues, see MLB Rival Leagues. The files are all in MSExcel format. So, use your "Save Target As" command to save them to your hard disk.
All teams for all years: 1890-2007