There is nothing like spending some time far beyond the west bank of the Potomac to influence your perspective on Washington business.

A week in the offices, factory floors and living rooms of a typical Midwestern manufacturing center like Rockford, Ill., is long enough to develop new insight into Coach George Allen's old truism: "The future is now."

The future of America, Washington's business thinkers will tell you, is a high-technology, post-industrial society. The nation has evolved from an agricultural economy to a manufacturing base and is on the way to becoming an economic system dominated by services in which the fast-food purveyor is more important then the farmer, the information network more vital than the assembly line.

Washington is there already. Quick, try to think of where the nearest factory is and what it makes. Manufacturing is a minor league game in this town.

The 77,000 bartenders, waitresses, busboys, cooks and clean up people working in local eating and drinking establishments easily outnumber the 62,000 manufacturing employes in the region. The District of Columbia is so short on factory work that this newspaper is its largest "manufacturing" employer. Only one in every 20 private sector jobs in the metropolitan area is considered manufacturing work.

But if the high-tech, post-industrial future is already the way Washington lives, what about the rest of the country? The Washington economic model is not so easily accepted in the Rockfords of America. When 40 percent of your jobs are in manufacturing, it is hard to envision a post-industrial lifestyle that offers much beyond unemployment checks.

As economic evolution progresses, Rockford will have to continue to live through changes that Washington has never had to face. Ever since the founding fathers staked out the Potomac swamp as a national capital, the local populace has serviced the central government in one way or another. Private sector jobs now outnumber government employment by two-to-one and service jobs alone will probably surpass government work by the end of the decade.

The local service economy has gradually evolved over decades. From printing presses to electronic data bases to computer communications research centers has been a predictable progression in Washington's economic history.

While Washington business executives have seen their smooth growth curves kinked by the recession, Rockford's economic indicators have fallen off the charts. Rockford's biggest car dealer saw his sales collapse from 3,000 cars in 1979 to 1,375 last year; the Rockford area lost 15,900 jobs in the last three years; the unemployment rate is still 16.8 percent while the Washington area is down to 4.9 percent (10.3 percent in the District).

What is happening in Rockford is what would happen to Washington if President Reagan kept his promise to cut the size of government and actually fired several thousand bureaucrats. (Fortunately for Washington, rhetoric comes easier than RIFs and the local federal payroll has increased by more than 1,000 jobs in the last year.)

Rockford businesses are being forced to fundamentally reassess their way of working and they are changing their operations in ways that would shatter the business-as-usual attitude of Washington.

Interview a Rockford executive and you'll meet someone in the midst of a mid-life crisis. A thermostat maker is now producing computerized environmental controls. A machine tool company that's been into auto assembly lines almost since Henry Ford's time now makes computer-controlled machines that can carve a cruise missle from an aluminum tube. Even the Nylint factory that makes toy trucks is automating to fight foreign competition.

"Lean and mean" has become the motto of executives whose ability to cut costs makes David Stockman look like a spendthrift. The administration's failure to reduce the size of the federal deficit gets little sympathy from Rockford's Republican executives, all of whom have slashed their own overhead.

"There isn't a budget that can't be cut 7 percent," Illinois Board of Education member Richard Rundquist told me. Rundquist knows. He put the crew at his small foundry on four-day weeks and had his wife take over bookkeeping chores to get through last year.

What is surprising about the wrenching economic change under way in Rockford is the attitude of the city toward what is happening. There is an extraordinary willingness to change, a willingness to make sacrifices, to accept painful adjustments that is rarely seen in Washington, where special interests protest the slightest threat to their status quo.

Call it Calvinist guilt, if you will, but there is in Rockford an unspoken recognition that all is not right with America, that hard work and self-denial are needed to make it well again. A painful recession has taught the city that outmoded management, unproductive plants and poorly motivated workers cannot compete with the Sunbelt, the Japanese or the Third World. They must either change or die.

Reluctantly, Rockford is preparing itself for the post-industrial economy that Washington already enjoys. But the lesson I learned in a week out there is not that Washington's high-tech service economy should become the model for Rockford or the rest of the nation. It is that Rockford's resiliance, its adaptability, its acceptance of change, is what the whole country needs to see it through the next decade.