Let's say you live in a typical American subdivision built in the last 30 years, maybe one that looks something like this:

If you do, you probably know there's no topsoil.  But there was topsoil before that virgin prairie/forest was flattened to make garages for SUV's and safety playgrounds for safe kids, right?  What happened to it?

Well, we can't use topsoil as structural fill -- dirt that goes under houses and streets.  It gets stripped off the project site first, and buried in non-structural spaces, like easements.  That's the strip highlighted in the next image:

It could be 10 feet wide or 30.  There could be 6 inches of topsoil buried there, or maybe 8 feet or more.  There might be some, but buried under several feet of mineral soil.  Or, as this only applies to fill areas (where the grade was raised from the original, as opposed to cut areas) there might be none.  One near certainty is that there won't be any close to the house.

But on the  off chance your backyard is in the right spot, it doesn't hurt to take a shovel, dig a hole by your back fence, and see if you find that buried topsoil.  It would make an excellent spot to plant trees (thus blocking your view of the naked elderly neighbor), and deep-rooted nutrient raisers like comfrey.

A bit more complex arrangement:

If you can get your hands on the original grading plan at your local planning authority, it should show where the cuts and fills were.  Otherwise, Google Maps and guesswork might pay off.  Or not.

Somewhere out there, a permie might find this to be useful information.

Cheers!