Obama is announcing his plan for changing the No Child Left Behind law, including dumping the current mandate that every child in America score as "proficient" in reading and math by 2014 as "utopian."

But why does the federal government exercise effective control over local public schools anyway?

Back in the post-Sputnik era, a chief reason offered for federal intervention was the huge differences in wealth among the states demanded that the federal government pitch in to help equalize resources. Yet, it's not clear to me that those between-state differences are all that important anymore as cost-of-living differences have emerged. For example, up through 1975, California had both a highly productive economy and housing costs no higher than the national average. So, sure, it was easier then for California to afford schoolteachers (not to mention a fabulous system of public universities) than it was for Mississippi. So, the argument went, if there was some smart kid in Mississippi, he might not get as good an education as if he was in California, and therefore the federal government should supplement state and local spending on education.

Today, though, differences in spending ability between states have been rendered less striking by higher costs-of-living in high income states. And, indeed, that old-fashioned argument for federal involvement in schooling has largely disappeared.

Today, in contrast, the obsession of the federal No Child Left Behind act is with closing the racial gaps in students' performance — which are virtually the same in every state (and even in every school district) in the United States. So, what is the justification for federal involvement?

It's not as if some states or school districts have discovered solutions for racial gaps, and the federal government only needs to impose those solutions on a few recalcitrant bigoted states. In fact, the most liberal of the 51 "states," the one that is most under control of Congress, the District of Columbia, has by far the largest white-black gap in test scores of any in the country.

So, if nobody has yet discovered how to close the racial gap, then why federalize education? Why not let 51 flowers bloom and see if anybody comes up with a solution?

Why not have more competition between states and between school districts within states? In Southern California, the suburban San Gabriel Valley long played second fiddle to the more close-in suburban San Fernando Valley, but the San Gabriel Valley has surged ahead in recent years, largely because it has a wide variety of competing school districts, such as Arcadia (where my cousins went to public school) while most of the San Fernando Valley is under the not very competitive Los Angeles Unified School District.

So, why reproduce the LAUSD on a national scale?

Clearly, the main reason for the tightening grip of the federal government on local education is simply that the most ambitious politicians, such as Bush and Obama, go into federal politics and they grab the most appealing issues (Fix the schools!) and try to deal with them at the federal level.

That's not a good reason.