When Houston was competing with a Brazilian city to be the site of a Japanese-owned plant, Houston could provide the Japanese with pertinent information about the educational attainments and other qualities of its workforce and the number of Japanese speakers in the area. The plant is in Texas partly because Houston had superior statistics, thanks to an inexpensive federal program currently under attack from some conservatives. They may not know that its pedigree traces to the Constitution’s Framers.

These Enlightenment figures — rational, empirical, inquisitive — believed in the possibility of evidence-based improvements. And they mandated the “enumeration” of the population every 10 years. James Madison soon proposed expanding the census beyond mere enumeration to recording Americans’ occupations. And compliance with the survey was compulsory.

During America’s post-Civil War dynamism, President Ulysses Grant proposed a census every five years to keep government abreast of change. Beginning in 1940, a small percentage of households was required to fill out what came to be the “long form.” And since 2005, this has been replaced by the American Community Survey that about 3.5 million households a year are required to complete, providing demographic, economic and social information pertinent to government and private-sector activities.

The government still makes mandatory the mild duty of providing information pertinent to governance. This is why some conservatives oppose continuing the ACS. Distrust of the politicized IRS, with its mountains of sensitive information, and anxiety about the National Security Agency’s collection of metadata have deepened Americans’ instinctive suspicion of government, which is healthy. But the ACS should not become collateral damage.

If the survey were voluntary, compliance would plummet and the cost of gathering the information would soar. The data, paid for by taxpayers and available to them at no charge, serves what the nation needs most — economic growth. Target, Wal-Mart and other large retailers tailor their inventories to regional, even neighborhood differences revealed in the ACS’ granular data.

Information improves the efficiency of markets — and of governments, too. There are systemic reasons why democratic governments frequently behave foolishly: Politicians’ constant incentive is to confer current benefits on targeted beneficiaries and to defer costs (by running deficits). Hence there are weak incentives to formulate government policies with the quaint characteristic of measurably ameliorating broad social problems. The ACS cannot cure systemic problems, but abolishing it would require government to be unnecessarily ignorant.

Some incandescent conservatives propose forbidding the ACS to ask about respondents’ religious beliefs and practices. But it does not ask. It is more interested in, for example, at what time respondents leave home for work, information that helps local governments plan traffic flows. The ACS does not seek to identify illegal immigrants, but by asking respondents their ethnicity, if they are citizens and how long they have been in the country, it informs public debate by estimating the number of illegal immigrants.

Secrecy is government regulation — the rationing of information. The collection and dissemination of useful information by government serve the deregulation of life by empowering the public to direct the government, to judge its performance, and to decrease dependence on government by invigorating the private sector.

In the absence of data, politicians pluck factoids from the ether, as Barack Obama did in this year’s State of the Union address: “Every dollar we invest in high-quality early childhood education can save more than seven dollars later on, by boosting graduation rates, reducing teen pregnancy, even reducing violent crime.” Such facially implausible and utterly unsubstantiated claims flourish when there is indifference to information.

The Welfare Reform Act of 1996, which was applied conservatism, happened because empirical data convinced enough Democrats of the costs of welfare dependency. Charles Murray, the most consequential and conservative contemporary social scientist (“Losing Ground,” “Coming Apart”), depends on ACS and other census surveys.

Clearly, conservatives should favor the nation applying to itself the injunction “Know thyself.” Besides, if conservatives do not think information about society — the more the merrier — strengthens their case, why are they conservatives?