On Wednesday night, the Republican-controlled House approved the U.S. Census Bureau budget with one big change: GOPers voted to eliminate funding for the annual American Community Survey on the grounds that it’s not required by the Constitution and is an invasion of privacy.

“It’s an absolutely terrible decision—it’s terribly shortsighted,” says David Cooper, an economic analyst at the nonpartisan Economic Policy Institute.

And sure, a number-cruncher would say that. But why should you care? Well, here’s how the Census Bureau describes the survey:

The American Community Survey (ACS) is an ongoing survey that provides data every year — giving communities the current information they need to plan investments and services. Information from the survey generates data that help determine how more than $400 billion in federal and state funds are distributed each year.

What this means: The ACS is a crucial resource for anyone interested in the distribution of federal dollars and local trends. (Like, say, demographic shifts in D.C. neighborhoods!)

“The ACS is a really powerful survey because it has a huge sample size,” Cooper says. “The sample size is 2.9 million households. Because it engages such a large swath of the population, it lets you analyze trends, even in small states.”

Without the ACS, states like North Dakota and Rhode Island—and non-states like our dear District—would have to rely on the (less detailed) data that comes out every 10 years from the decennial U.S. Census.

And, even more importantly for D.C., it collects data on where people work, not just where they live. That means it provides useful stats on the impact of policies in a town like ours, where hundreds of thousands of people commute from Maryland and Virginia to work. The only comparable survey to the ACS is the Current Population Survey—but its sample size is considerably smaller and the data is far less granular.

“Without [the ACS] we really wouldn’t have a reliable way to look at income, poverty, and housing costs on the state level,” says Jenny Reed of the D.C. Fiscal Policy Institute.

Is there any merit to the privacy claim? Both Reed and Cooper say no. “There’s all sorts of privacy controls,” Cooper says. “Information is top-coded so you can’t identify people.”

Of course, this makes us think of another trend: All the crazy legislation the House just can’t seem to sneak past the Senate. Which means it’s really unlikely the ACS will go anywhere.

Correction: Due to a reporting error, this post originally stated that responding to the ACS is not mandatory. It is mandatory. Though you probably won’t go to jail if you don’t respond.

Photo by jcolman via Flickr/Creative Commons Attribution Generic 2.0 License