U.S. Appropriations by Fiscal Year
Congressdotgov tweeted about this resource earlier today.
It’s a great starting place for research on U.S. appropriations but it is more of a bulk resource than a granular one.
You will have to wade through this resource and many others to piece together some of the details on any particular line item in the budget. Not surprisingly, anyone interested in the same line item will have to repeat that mechanical process. For every line in the budget.
There are collected resources on different aspects of the budget process, hearing documents, campaign donation records, etc. but they are for the most part all separated and not easily collated. Perhaps that is due to lack of foresight. Perhaps.
In any event, it is a starting place if you have a particular line item in mind. Think about creating a result that can be re-used and shared if at all possible.