While getting primary sources online was a feat in itself in 1998, teachers were central to the vision.  The first installment of History Matters was funded by W.G. Kellog foundation.  At this same time ASHP was working with the NEH New York teacher development.  Thus, the History Matters producers brought these resources together to appeal to the NEH's interest in teaching.  

That they already had content, servers, interpretive contextual material from professional historians and a clear vision for expansion. In hindsight, History Matters seems like it was an easy sell.  They proposed to more than double primary sources and far exceeded the proposed goals over th course of it's funding. It might also be important to note that as the historical thinking and document analysis how-tos developed, a collaboration with Visual Experiment at Georgetown university developed as well.