I will add a tidbit to the tweet above:
USCIS up until 2017 ran a budget surplus from filing fees alone:
$3 billion in revenues. $6 M surplus.
Then Genius trump canceled Premium processing which amounts to $500 million of those revenues, costing USCIS a total loss of about $700M

— ALT-immigration (@ALT_uscis) October 29, 2018