If I search a tool like JSTOR, ProQuest, or Academic Search Complete, I typically just find secondary sources. Occasionally I can find primary sources there, but only when it is part of a translation or transcription project, but it is rare for me to find these appear in my results. Sometimes I can find books that compile these, but one $20 book might contain just 40 primary sources, which seems minuscule.
I'm looking for US History resources like letters, dairies, military orders, military reports, commission reports, etc.
Is there a search tool that compiles a vast database of primary sources?