Minor League Home/Away Uniforms - When and How Widespread?
 

I am tentatively starting a personal project of collecting images of minor league baseball uniforms to aid in researching and identifying photographs, but have what I hope is a quick question (or series of questions) before embarking on what I'm sure will be a lifelong effort:

How common was it for minor league teams to have different uniforms for away games, and was there a general date around which it became more common? Did it vary by leagues, or by team? (Presumably team finances would have also played a part?)

I'm just trying to get my head around how many variations for each year/team there could be, not that I could ever pursue this to 100% completeness. I know it's a crazy venture, but it's something that will be built on over time. I just need to get some kind of structure in place to keep track of all the images and hopefully have some idea of when to check off years/teams from the "missing image" list.

Any input or suggestions of good sources for "ID'd" images (team/year, not necessarily player names) would also be appreciated :D