For an eighth consecutive year, Minnesota can lay claim to being best in the nation in the ACT college admissions test.

State seniors again posted higher scores than those in other states in which at least half of students took the exam.

Progress was made, too, in the percentage of state graduates deemed college-ready in each of the four subject areas being tested.

This year, 39 percent of Minnesota seniors were proficient across the board, compared with 36 percent in 2012.

"That is tops in the nation," state Education Commissioner Brenda Cassellius said Tuesday.

Results were mixed, however, in another chief area of concern: the large, persistent gap between white and minority test takers.

According to the results to be released Wednesday, 61 percent of the state's white students reached the minimum college-readiness benchmarks in at least three of the four subjects tested, up from 59 percent a year ago. Black students who met the same standard remained at 16 percent.

For black seniors, that was an improvement over 2009, when 14 percent of test takers were college-ready in three subjects. But it was still short of the five-year high of 17 percent in 2011.

American Indian, Asian and Hispanic students also saw the gaps widen between themselves and white students on the college-readiness front, the results show.

Said Cassellius: "We absolutely have to always address the achievement gap."

She said that she had not seen the college-readiness comparisons. She emphasized, instead, that each of the state's student subgroups — with the exception of Asians, a Star Tribune review of the data later revealed — had outperformed their national counterparts.

That accomplishment, the commissioner said, was more notable than the state's continued first-place ranking.

This year, Minnesota's average composite score was 23, up from 22.8 in 2012, out of a possible 36. Seven other states had scores that were the same or higher, but in each case less than half of the state's students participated.

About 74 percent, or 44,676, of Minnesota graduates took the ACT. Massachusetts, which recorded the highest average composite score — 24.1 — saw only 22 percent of its graduates take the test.

For the ACT, students are tested in the areas of English, math, reading and science. The results that are to be released Wednesday include not only composite scores, but also a gauge of how well prepared students may or may not be for college coursework.

College readiness is defined as the score that a high schooler needs to achieve to have a 50 percent chance of earning at least a B and a 75 percent chance of getting at least a C in a college class.

Thirty-one states had more than 40 percent of their students take the ACT. In only two of them — Minnesota and Wisconsin — did more than half of the graduates meet at least three of the college-readiness benchmarks.

In Minnesota, 78 percent of students were college ready in English, the highest percentage by subject area. The lowest was in science, with 52 percent of students being proficient, up from 42 percent a year ago.

The 39 percent deemed this year to be college ready in all four areas marked the high point for that statistic in the past five years.