Gardendale, Ala., high school biotech teacher Justin Ingram readies his classroom before school begins in August. A new study says the U.S. is headed toward a serious teacher shortage. (Linda Davidson/The Washington Post)

The United States is facing its first major teacher shortage since the 1990s, one that could develop into a crisis for schools in many parts of the country, according to a new study by the Learning Policy Institute, an education think tank.

The shortfall is a result of increased demand for teachers as schools reinstate classes and programs axed during the Great Recession. It has been compounded by a dramatic decrease in the supply of new teachers entering the profession. Enrollment in teacher-preparation programs dropped from 691,000 in 2009 to 451,000 in 2014, a 35 percent decline, according to the study, “A Coming Crisis in Teaching? Teacher Supply, Demand and Shortages in the U.S.”

“Our analysis estimates that U.S. classrooms were short approximately 60,000 teachers last year,” Leib Sutcher, the study’s co-author, told reporters Tuesday ahead of the study’s release. “Unless we can shift these trends, annual teacher shortages could increase to over 100,000 teachers by 2018 and remain close to that level thereafter.”

[Think teachers aren’t paid enough? It’s worse than you think.]

The impact of the teacher shortage on students, according to the study’s authors, will be schools having to cancel courses, increase class sizes and teacher-pupil ratios, or hire underprepared teachers.

Although nearly every state has reported teacher shortages to the U.S. Department of Education, the problem is much more pronounced in some states than others. But across the country, the shortages are disproportionately felt in special education, math and science, and in bilingual and English-language education.

Regardless of the state, students in high-poverty and high-minority schools are typically hit hardest when there are teacher shortages. In 2014, on average, less than one percent of teachers were uncertified in low-minority schools, while four times as many were uncertified in high-minority schools, the study showed.

Teacher attrition — the number of teachers leaving the profession for a variety of reasons — remains high and is the single-biggest contributor to the shortage, according to the report. Nearly two-thirds of the teachers who leave the profession do so before retirement age and cite dissatisfaction with their job as the reason. Addressing the job-dissatisfaction issues could help avert a teacher crisis.

“In times of shortage, policymakers often focus attention on how to get more teachers into the profession, but it’s equally important to focus on how to keep the teachers we do have,” Sutcher said. “Reducing attrition in half, from eight percent to four percent, would virtually eliminate overall shortages.”

[From 2015: Study finds far fewer new teachers leaving the profession than previously thought]

Linda Darling-Hammond, president of the Learning Policy Institute and one of the study’s co-authors, pointed out that teachers make about 20 percent less than other college graduates and that teacher salaries have lost ground since the 1990s. That despite increased teaching hours and less time for classroom preparation.

“In more than 30 states, a mid-career teacher heading a family of four is eligible for government assistance,” she said.

Darling-Hammond recommended increased pay, compensation packages that could include housing and child care, and forgivable loans as some of the ways to improve teacher retention.

The study, based on federal data sets and more than a year in the works, received acclaim from powerful political figures on the education front.

“This research underscores the importance of offering effective incentives to keep our best teachers in the profession, contributing their expertise to help others,” Sen. Lamar Alexander (R-Tenn.), chairman of the Senate Health, Education, Labor and Pensions Committee, said in a statement.

Former education secretary and South Carolina governor Richard W. Riley concurred.

“The teaching workforce is so critical to our future, and what we see here is the data we need to help us move forward with thoughtful, effective strategies,” he said.

An accompanying report, “Minority Teacher Recruitment, Employment, and Retention: 1987 to 2013,” looked specifically at the effort to increase the number of minority teachers in schools.

“Teacher turnover is especially high in poor and disadvantaged schools,” said Richard Ingersoll, that report’s author. “What the data tell us is that we need to focus on more recruitment of minority teachers but also more retention of minority teachers if we ever want to have the teaching force look like the student population in schools.”

Although compensation was a factor for minority teachers, it wasn’t the only one, Ingersoll said.

“We need to work on working conditions,” he said. “Among the key conditions that drive out minority teachers are a lack of autonomy and discretion in the classroom.”