OVER THE next few years, the government will determine how much political representation and federal money your state gets. That crucial process is off to a lousy start.

Commerce Secretary Wilbur Ross told a House panel Thursday that the 2020 Census will cost an additional $3.3 billion, a 27 percent funding hike from earlier estimates. The 2020 count was supposed to be different, leveraging satellite imagery to create a database of U.S. addresses, relying on online rather than mail-in responses, and using troves of data that private companies have collected to fill in gaps. These and other money-saving innovations were supposed to keep total costs about flat since the last big count, in 2010.

But it has not worked out that way. These changes required some upfront investment, and Congress has refused to appropriate the necessary cash, underfunding the Census Bureau year after year while the bureau should have been preparing. It has had to cancel a variety of important tests of its new systems, along with end-to-end field tests that had been planned for next year. Without the testing, the bureau will have to rely more on older, more expensive counting methods.

This penny-wise, pound-foolish approach means that, with hardly any time left before the counting must commence, Mr. Ross must go to Congress begging for money to cover the inevitable cost overruns. The current projection is that the 2020 Census will cost $15.6 billion, when the bureau previously figured it could keep costs at about $12 billion with a few smart changes. That may have been unrealistic, but anything close to that level would have been a real accomplishment. Population growth and inflation both push up costs between counts, as does the fact that fewer and fewer people are responding to the first wave of mailed census forms, which in turn requires more census workers to knock on doors in order to ensure an accurate count.

At stake is more than just a fascinating report on American demography. Congressional seats and electoral college votes are apportioned to the states according to the decennial census numbers. The federal government depends on the figures to distribute more than half a trillion dollars. Businesses of all sorts rely on solid federal population data to decide what to produce and where to sell. Historically, the census has undercounted poor and minority communities. Without better procedures, federal officials may do so again, potentially shortchanging Americans who deserve to be considered. Accurately counting every American is a responsibility so critical that the Constitution itself explicitly obliges the federal government to do so.

Congress must attempt to salvage the foundering 2020 count. It should not feel bound to meet only Mr. Ross's suggested funding levels but rather to determine whether they should be exceeded. Some in Congress have already concluded as much. Moreover, lawmakers must examine what is happening at vital-statistics organizations across the government. Politico published Wednesday a damning report showing that agencies that collect information on U.S. businesses, employment, wages and a variety of other things are struggling because of congressional shortsightedness.

Neither Congress nor the executive branch can wisely govern the country without knowing what it looks like.