Hi Fred. To convert this to something more familiar, you can first convert it to cubic feet:

1 mile = 5280 ft, so (1 mile)³ = (5280 ft³) = 5280³ ft³ = 147197952000 ft³.

Now we can convert that to some more familiar volume measures.

Each foot is 3.048 decimeters (dm) and since 1 dm³ is a litre, we have:

147197952000 ft³ = 147197952000 (3.048 dm)³ = 147197952000 x (3.048³) litres = 4168181825441 litres.

If you prefer US gallons, you need to look up the conversion: 1 ft³ = 7.48051948 US gallons, so

147197952000 ft³ = 147197952000 (7.48051948 US gallons) = 1101117147352 US gallons.

Big numbers like these are rather hard to picture. That's about as much water as flows over Niagara Falls in about a month.

Another comparison: The land area of Manhattan Island in New York City is 22.96 square miles. So if we divide 1 cubic mile by 22.96 square miles, we have 1/22.96 miles = 230 ft. So if you built a retaining wall
around Manhattan and poured 1 cubic mile of water into it, only buildings taller than 23 stories would break the surface!

Cheers,
Stephen La Rocque.