It's coming along. There are over a thousand pages now, including narrative from my lectures (in green), additional information on topics of interest (in blue), and about 135 Primary Sources (in orange). The sources have audio files where I read the source, and there are ten lecture videos as well. I'm about 2/3 of the way through the bare-bones implementation of this course in this format. Over time, of course, I'll continue adding. Both to the narrative, to allow it to branch and maybe even go to slightly different "places" in a particular chapter (such as allowing readers to mainly focus on a primarily social or cultural or economic perspective on a period, for example); and also in the supporting topics. As I think I've mentioned, I'd like to add a lot more on the influential families of American history. This would come from my research on the origins of the gilded age. I'd also like to focus a bit on business and finance. And on the history of American medicine. These would be adjacent and might run parallel to the main story of the US History students ought to learn in a survey course. But it would link to it and offer additional context and interesting content readers could pursue.
Another set of content I'm considering rolling into this web of history is the research and writing I've done on my own areas of historical interest. The freethinkers, for example; but also the peddlers and the peppermint kings and Yankees like the Ranney family spreading out from the east coast (Middletown, Connecticut) to the early frontier (Ashfield, Massachusetts) and then the Yankee West (Phelps, New York and White Pigeon, Michigan). It seems a bit odd that historians often avoid making their "survey" writing too particular, but I think if it's adjacent material, this type of content might help readers appreciate the work that goes into focused history-writing on new research; which is ultimately what makes surveys possible.
I've also played around, in the past, with giving students a glimpse under the hood of historiography. For example, in my American Environmental History textbook, I included a review of a foundational monograph in the field, at the end of each chapter. So the chapter in which Europeans "discover" the Americas includes a review of Crosby's The Columbian Exchange and the early American industrialization chapter has a review of Steinberg's Nature, Incorporated. I'm considering adding these types of monograph reviews to the US History Web at some point. Maybe also some readings of big US Histories from the past. By people like Bancroft or Hart or Beard to start, and then more recent authors like Schlessinger, Woodward, Hofstadter, Foner, Cronon, and Richardson. That doesn't replace the need for people to read these books themselves, of course. But it could help them decide which books they'd like to read.
Maybe I'll just turn this into a really big web of linked history. I should call it something unpretentious, like "Dan's History Web".