I find it extremely helpful to convert any big US-wide number a per-capita value, which you can easily estimate in your head by multiplying by 3 and dividing by a billion. As a random example, the US spends $55 billion on pets annually, which is just an arbitrary number to me. But convert this to about $165 per capita and now it's much easier to see if this number is reasonable, compare it to other expenditures, etc.

(And then there's the satirical visualization from Saturday Night Live: How big is a $16 trillion dollar debt? Imagine each of these dollar bills represents one trillion dollars. It would take a stack of 16 of them to equal $16 trillion dollars.)