A 2013 photo of the Columbia University campus in New York City. (Mario Tama/Getty Images)

Columbia University filled about 45 percent of its freshman class last year through the binding application process known as early decision, school officials said.

A Washington Post article last month about early decision found that dozens of prominent schools use early decision to fill a third or more of their enrollment. The early decision system requires students to enroll if they are accepted and to withdraw all other applications — a process that explicitly shuts out those who want or need to compare multiple financial aid offers. Another process, known as early action, allows students to apply to a school early but to continue to shop around until May 1 to make a final decision.

The Post’s analysis was based on information that colleges supply annually to U.S. News and World Report and others through a questionnaire called the Common Data Set. But Columbia was not included in the analysis because it declined to release its Common Data Set answers.

The elite private university in Manhattan is the only school in the eight-member Ivy League that refuses to routinely publish Common Data Set answers on its website. Outside the Ivy League, a few other prominent schools also take that nondisclosure position. The University of Chicago, for instance, also routinely denies public access to its Common Data Set answers. But Chicago does not have an early decision admissions program.

This week, Columbia officials provided The Post with detailed data on early decision and admissions for the Class of 2019 cycle. For this class, which entered last fall, 3,373 students applied to Columbia through early decision. Of those, 632 were admitted — resulting in an early decision admit rate of 18.7 percent. The university’s total admit rate, counting students who apply in the regular cycle, was 6.1 percent. It is often the case that early decision applicants are admitted at a much higher rate than the rest of the applicant pool.

The university enrolled 1,398 freshmen last fall. The early admits accounted for about 45 percent of that total.

The most aggressive user of early decision in the Ivy League is the University of Pennsylvania, which fills about 54 percent of its class through the binding process. U-Penn., like Columbia, pledges to meet full financial need of all students it admits.

Here are the Common Data Set website links for the other seven Ivy League schools: Brown, Cornell, Dartmouth, Harvard, U-Penn., Princeton and Yale.

Harvard, Princeton and Yale do not use early decision. Instead, they use a restrictive form of early action that allows students to apply early to only one school but make an enrollment decision by May 1.