For those who like to know the details of how much money the US government takes in (and from where) and how much it spends (and on what), the US Treasury publishes a wealth of figures.
In particular you can see the activity in its ‘checking account’ on a daily basis. Thursday, July 28th is the last day for which the figures are available and we are told that the government started the day with about $74 billion, took in $112 billion and spent $132 billion, leaving it at the end of the day with $54 billion.
You can see what is causing concern if you look at the last column that gives the fiscal-year-to-date figures. (Note that in the US, the fiscal year starts on October 1 and ends on September 30 of the following year.) It shows that the government started the fiscal year with $310 billion, and for the year so far had receipts of $9,108 billion and expenditures of $9,364 billion. So we have had a drop of $256 billion in just ten months, an average burn rate of $26 billion per month, which is why we are so close to emptying the account.
But the monthly figures can fluctuate wildly so the average rate is not a good predictor of what will happen in the short term. (Caution: When reading the monthly table, note that for some reason monthly deficits are entered as positive numbers and surpluses as negative.)