An increase in drug-related arrests and stricter sentencing requirements have brought about a 7.4 percent hike in the number of inmates in federal and state prisons, but prison capacity hasn't kept up, according to the Justice Department.

At the end of 1988, a record 627,402 men and women were incarcerated nationwide, but the most optimistic estimate of prison capacity said there was room for 566,898. While the prison population was increasing by 7.4 percent, the prison capacity was increasing by just 5.5 percent."The 1988 increase translates into a nationwide need for more than 800 new prison bed spaces per week," said the report written by Lawrence A. Greenfeld, corrections unit chief for the department's Bureau of Justice Statistics.

The report released Sunday said the 42,967 additional prisoners in 1988 were about 3,500 more than the number added during 1987. There had been a 7.2 percent hike in 1987 over the previous year.

The report attributed the increases both to the heightened likelihood that a serious offender will receive a prison sentence and a 113 percent increase in the number of adults arrested for drug trafficking or manufacturing.

And the Bureau of Prisons expects the increases to continue.

"Obviously, the increased efforts of law enforcement to combat drug problems (will hike the population), as well as the new sentencing guidelines under which inmates will be serving longer sentences," said Greg Bogdan.

The federal prison population, which stood at 49,928 at the end of 1988, a 3.4 percent increase over the 48,300 at the end of 1987, is expected to reach some 83,500 by 1995, Bogdan said.

The report said that nationwide, state prisons were operating at 7 percent to 23 percent over capacity, while federal prisons were estimated to be between 33 percent and 72 percent over capacity. Bogdan said the federal prisons were operating at an average of 55 percent over capacity.

During 1988, total state and federal prison capacities increased by 28,000 to 31,000 beds.

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(ADDITIONAL INFORMATION)

A double bind

The states that have more than doubled the number of "sentenced prisoners" since 1980 were Utah, Arizona, Colorado, Delaware, Hawaii, Kansas, Massachusetts, Missouri, Nevada, New Mexico, New York, North Dakota, Oklahoma and Pennsylvania.