I know how much you make, whether you really have that advanced degree you claim and if you are spending too much of your paycheck on your mortgage.

Well, not exactly. But I do know as a group and on average what you and your neighbors earn, how much you and your neighbor group make, what level of education you've attained and what percentage of your income goes to paying your mortgage.As well as your race, if you send your kids to private school and whether there are gay couples, the foreign-born or - no! - renters in your midst.

Who knew the Census Bureau nerds could come up with such fodder for the nosy, when normally we - um, I mean they - have to find out about their neighbors' secrets via dinner party gossip or the contents of their recycling bins.

On Tuesday, the Census Bureau unloaded the largest cache of data in its history: demographic tidbits from its American Community Survey, a veritable WikiLeak of who we are and where we live. Conducted annually - using a 1 in 10 sample - the survey tallies data about age, race, income, housing, commuting and education from 2005 to 2009.

As The Baltimore Sun reported this week, some important local and national trends emerged from all those numbers: Maryland remained the country's wealthiest state, we're getting smarter - or, at least, more educated - and more immigrants were moving to the suburbs.

The real fun, though, comes in checking out the results from the neighborhood level, and finding out how your small piece of the world compares to everyone else's. The New York Times, with its "Mapping America: Every City, Every Block" feature, has overlaid the data onto maps on which by zooming in, you can see almost down to your own house.

Some of what you find merely confirms the obvious - the income spread in our area, for example, tracks generally with the "nice" neighborhoods in the city and counties. On the education front, there are lots of people with master's and higher degrees in a swath that begins around the Johns Hopkins' Homewood campus and heads northward. And then there are other pockets of the pedigreed around the growing biotech parks, which make me wonder if some of those scientists are sleeping in their labs.

Of course, what the maps reveal most is that like clusters with like - that people of similar means and schooling tend to live in the same communities. The whole Not Our Kind, Dear phenomenon.

The other thing that the maps show is that census tracts don't always coincide with true neighborhoods. My slice of Federal Hill, for example, is part of a fairly sprawling tract that encompasses Ridgely's Delight to the Inner Harbor as well. Not to be too provincial - something no Baltimorean ever gets accused of, right? - but these are pretty disparate parts of town.

Checking out my tract, I learn our median income has declined, home values have risen and 1 percent of the estimated 1,995 households, or almost 20 of them, were unmarried same-sex couples.

That last estimate shows that sometimes you're dealing with such small numbers that you're probably not getting a true reflection of things. There are too many census tracts, even ones that include parts of Federal Hill, Inner Harbor East and Canton, for example, where the "unmarried same-sex couples as percentage of all households" category is said be 0 percent. Doubtful.

Also in my tract, and nearby ones, the sample size gathered up too few elementary school kids to determine what percentage of them went to private school. And what, by the way, is up with one census tract that includes Guilford and Tuscany-Canterbury, where 100 percent of the kids go to private school?

(I'm not sure what map The Times is using, but this tract includes a patch, I kid you not, identified as "Dog Poop Park." Funny, I always thought that was Robert E. Lee Park.)

Even if what you're getting on these maps is necessarily distorted by sample sizes and such, it's a little unnerving to spy, virtually at least, on your neighbors. Given what they say about good fences, it's a good thing whoever draws up the census survey questions isn't as nosy as I am - I mean, as some people are.

jean.marbella@baltsun.com