NO MATTER how divided, America comes together every ten years for the census. It is the single event in which everyone, regardless of creed, colour or even citizenship, is supposed to take part. Few government agencies could boast that their mandate was enshrined in the constitution, as the Census Bureau can, thanks to the impassioned arguments of James Madison, who thought that future legislators should “rest their arguments on facts, instead of assertions and conjectures”. But that noble mission may be jeopardised by inadequate preparations for the next census, due in 2020.

Spending usually rises greatly in the years before a census, to pay for testing and technology. But pending legislation would appropriate only $1.5bn for the 2018 fiscal year, nearly $300m less than needed, according to Terri Ann Lowenthal, a census expert. The Government Accountability Office (GAO) has placed the 2020 census on its list of high-risk projects. Lack of funding has already caused the bureau to cancel two of its three “end-to-end” tests, as dress rehearsals are called. John Thompson, the agency’s director, unexpectedly left in June; President Donald Trump has yet to nominate his replacement.

America’s census is an astounding, expensive event. In 2010 the Census Bureau amassed 550,000 temporary employees and spent $12.3bn trying to count every American resident. The GAO notes that costs have increased from $16 per household in 1970 to $92 in 2010. If an accurate tally is costly, though, an inaccurate one is probably more so.

Census counts determine the number of congressional representatives, as well as the boundaries of districts. Nearly $600bn of federal funding is allocated on the basis of census data each year, according to recent estimates by Andrew Reamer of George Washington University. Businesses rely on the numbers to identify stocks of skilled labour and latent demand for new branches. Target, a big retailer, uses the data to decide which items to stock on its shelves.

Because Congress has directed the bureau not to spend more than it did in 2010, it is planning to run the first high-tech census. The bureau wants to blend administrative data held by state agencies, use online maps and push internet response at an unprecedented rate. Those changes would save $5bn compared with the old methods, but must be rigorously tested in advance to ensure that the data are of high quality and secure. If that is not done, the bureau will be forced to default to older, more expensive methods.

Missing persons

Mr Thompson is more sanguine about the bureau’s challenges than others. What does worry him, though, is funding for the bureau’s outreach efforts. “You can’t get an accurate census without advertising,” he says. The bureau’s partnerships with community leaders, such as Baptist ministers in the rural South and Indian chiefs, help shore up response rates among groups sceptical of government. Civil-rights groups worry that many Latinos and Muslims will sit out the census, and lose political clout and public services as a result.

America’s other statistical agencies are also under strain. Stagnant funding for the Bureau of Labour Statistics (BLS), which produces market-moving numbers such as the unemployment and inflation rates, is making mistakes much more likely, says Erica Groshen, the BLS commissioner until January 2017. One error, caught at the last minute after a large retailer changed its reporting software, would have moved the consumer price index estimate by 0.2 percentage points. At that level, Social Security payments would have been wrong by $1.9bn per year. Because of flat funding, the BLS has suspended programmes tracking mass lay-offs and green jobs. Smaller statistical agencies like the Bureau of Economic Analysis, which produces GDP estimates, are also at risk. As Robert Groves, who led the Census Bureau in the last count, puts it, “They’re cutting into bone now.”