The license-plate stamping line at the state prison here may be the steadiest work in town.

Nearly one worker in four in the 78,000-resident city about 50 miles southwest of Chicago is unemployed--23.3 percent of the area work force in June, according to figures recently released by the Illinois Bureau of Employment Security. The figure is more than twice the average national unemployment rate, which was 9.5 percent in June and 9.8 percent last month.

Among cities, Joliet apparently has registered the highest urban unemployment figure reported in this recession, although it pales next to the 57.4 percent unemployment reported in Arizona's Greenlee County in June. The county, which has a work force of only 4,650 people, was rocked earlier this year by the closing of a giant Phelps-Dodge copper mine, by far the county's main industry.

But Joliet is no one-industry town. It has been beset by a variety of ills, which area officials say began with the closing of the Army's Joliet Arsenal a few years ago.

"They just closed up, lock, stock and barrel and blew away, and there went 7,000 jobs," says City Manager Ken Murray. Since then, Texaco Inc. has closed its Joliet refinery (800 jobs), U.S. Steel has closed its plant (800 jobs), GAF Corp. has scaled back operations at its building-shingle plant (700 jobs), and, in the most recent action, Caterpillar Tractor Co., the town's largest employer, laid off 2,000 of its 7,000 workers.

In addition, there have been cuts made by smaller employers, hiring freezes by others, and layoffs and closings among the retailers and other businesses that are supported by the town's workers.

"It has a rather devastating effect," Murray says. "This is a city that has lived off its industrial base, and the industrial base isn't there any more. A lot of our unemployment is not short-term unemployment, it's long-term unemployment."

"They've been cutting them all over," says Don Wirth, assistant manager of the Joliet office of the state Job Services Department. "It reflects all the way down to the gas stations or cafes who were thinking of adding another waitress or another attendant."

Joliet unemployment has been running consistently ahead of the national average for months. It reached 19 percent in March, during a round of temporary Caterpillar layoffs, and stood at 15.7 percent in May.

The high percentage of people out of work has had a negative impact the city's share of state sales and income tax revenues, leading to a freeze in city hiring. The high unemployemnt also is taxing city social services. And city officials say the impact has been cushioned somewhat by supplemental unemployment benefits from Caterpillar--although they worry that those benefits could soon run out.

State unemployment insurance offices are crowded, and the job services office, which attempts to find work for people unemployed for a long period of time, faces slim pickings.

Murray says Joliet's problems are chronic. Like many small Midwestern cities, its reliance on a base of heavy industry and its aging industrial facilities make a strong comeback difficult. "Joliet's an old industrial city and its industrial plant is old," Murray says. "Basically, we have to virtually reconstruct our industrial plant."

To do that, city officials have begun actively seeking out new industry less vulnerable to the economy's woes, particularly service businesses. Local banks are offering cut-rate financing for industrial construction and home-building, and while the results have not yet been cause for enthusiasm, building permit activity is showing signs of revival.

"If we could get some new businesses aimed at light industry, we could boom," Murray says.

For now, however, the town is bracing for a new round of Caterpillar layoffs in the fall, and hoping that the economy will bounce back.

"We're hopeful that the economists are right that we've hit the bottom of the recession and we'll see some recovery this fall," Murray says. "I have trouble believing our unemployment will get a lot worse than it is."