It was not long ago that some U.S. children were taught that American cows produce more milk than Soviet cows because cows are allowed to roam free in this country, according to educators who have studied U.S. and Soviet textbooks for more than a decade.

And until it was removed from the schools two years ago, a Soviet text, "Contemporary History (1939-84)," teaching about modern America, wrote that "monopolies get huge profits from cruelly exploiting black and colored peoples. . . . The criminal activity of racist organizations is not forbidden."

For more than a dozen years, a group of U.S. and Soviet academics has been toiling to remove factual errors and exaggerations from their textbooks. As the two nations focus on each other in preparation for this week's summit, participants in the joint U.S.-Soviet textbook project said that, while some problems remain, considerable progress has been made in making texts more accurate.

Historical and geographical errors are being corrected and most important, they said, educators and publishers in both countries appear eager to cool the propagandistic tones that have characterized textbooks for decades.

The joint project, which generally does not identify which textbooks have the distortions, will produce a report this summer. The project concluded last year.

"There have been very significant changes," said Barbara Flynn, an editorial vice president at Scott, Foresman. When the U.S.-U.S.S.R Textbook Study Project began in 1977, she said, "textbooks in both countries made fairly serious exaggerations of the weaknesses of the economy of the other country. They tended to focus heavily on the sore spots."

U.S. textbooks also have given little credit to the Soviets for their role in defeating Germany in World War II. And educators said there has been an emphasis on Soviet totalitarianism but little examination of the achievements of Soviet society.

At the same time, Soviet textbooks have concentrated on U.S. racial problems, describing American cities as massive ghettos where minorities are not allowed to enter professional occupations.

But changes are being made in some quarters. Flynn said that her company, for example, has been scrambling in recent months to update its social studies texts to include important recent developments such as the tearing down of the Berlin Wall and the end of the Soviet Communist Party's monopoly on power.

A spokesman for Houghton Mifflin said a 1990 edition of its high school history text has removed a discussion of the lack of freedom in the Soviet Union and included a section on President Mikhail Gorbachev's program of glasnost, or openness.

Although the Soviets, caught up in a rethinking of their past, have not produced new modern history texts yet, some Soviet schoolbooks have begun to change.

Vladimir Maksakovsky, a professor at the Moscow State Pedagogical Institute, wrote early this year in GeoJournal, a scholarly publication, that new Soviet geography textbooks had moved away from the "black and white" images typical of earlier publications.

The traditional text for grade nine, for example, "portrayed the U.S.A. as having 'instability of economy, growth of taxes, increasing inflation,' " he wrote. "The new generation of geography textbooks in the Soviet Union is removing such stereotypes."

Howard Mehlinger, dean of education at Indiana University and a professor of Russian history and chief of the American delegation in the project, cited a more specific change.

In the past, some Soviet books told of white settlers in the American West leaving blankets contaminated with smallpox near Indian villages in an attempt to decimate the Indian population. While some U.S. textbooks also contain this information, the U.S. delegation had objected to the Soviet interpretation: "Thus began more than 100 years ago the use of bacterial warfare against enemies."

Mehlinger said the Soviets dropped that statement.

Still, some academics cautioned that publishers in both countries have a long way to go.

"The Soviet Union is a huge country, and so are we," said Janet Vaillant, associate director of the Soviet and East European Languages and Area Center at Harvard University. "The idea that things are going to change overnight is absurd."

Much more interesting than any change in the Soviet treatment of U.S. history, Mehlinger and others said, is the upheaval in Soviet schools over the teaching of their own history.

Teachers have been working without history textbooks for two years, since the government declared that the official texts were ridden with "lies" about the past and prompted a national reexamination of history, reflecting Gorbachev's avowed determination to fill in the "blank spots" in the country's history since 1917.

American scholars say they are optimistic, on the basis of exchanges with Soviet scholars, that children there will be getting a more accurate picture of the United States.

The textbook project brought together dozens of Soviet and American academics, who exchanged assessments of each other's textbooks. It led not only to corrections, but to discoveries.

A few years ago, the Soviets complained indignantly, for example, that American textbooks frequently referred to Soviet revolutionary hero Vladimir Ilyich Lenin as "Nikolai Lenin," a breach considered equivalent to calling the father of the American revolution "Harry" Washington.

But upon further study, Mehlinger said, the Soviets found in their own research that Lenin used the name "Nikolai" on occasion.

The project also led, at least indirectly, to two joint publishing projects: Scott, Foresman is publishing a collection of essays written by U.S. and Soviet scholars on the history of their own countries, to be used by high school teachers.

McDougal Littell, a publishing house headquartered near Chicago, is issuing a text on World War II, written jointly and published both in English and Russian.

That project -- with the two countries agreeing on content and students in both nations using the same text -- would have been "far-fetched" only a short time ago, said Mehlinger.

"I think that's remarkable," Mehlinger said.