The "Columbia I.D. Required" sign hangs like a border crossing notice at the Head Sports clothing factory's retail outlet on the northern edge of what the borchures call America's "most dynamic new city."

"We realize we offend a lot of people," store manager Bonnie Simon said. "We promised the Baltimore and Washington dealers we wouldn't let anyone else in because it could hurt their business. We've got to make boundaries."

The boundaries that exclude most Howard County residents form the sportswear outlet are bolic and real and resented by those outside. Many of Columbia's rural neighbors are so disenchanted with the city's exclusive airs that they refuse to shop at the stores or go to the county hospital located within its borders.

Howard is a county at war with symbolic and real and resented by itself. The battleground is the new town of Columbia, risen between Washington and Baltimore and increasingly dominating the politics and, some say, the priorities of Howard County.

This is an odd sort of war, where peace talk alternates with harsh words between the new Columbians and the old countians who speak of each other almost as if they inhabit different nations sharing common borders and a mutual distrust.

"Columbia is not a community...Columbia is a way of life," blares the slideshow soundtrack at the new town's visitors center.

In the center of Wilde Lake and adjoining Clyde's, where plain hamburgers cost nearly $4, the visitors are bombarded by superlatives - "perfect unique and so different...better environment than anywhere...fantastic recreation bargain..."

Columbians go to natural childbirth and breastfeeding classes, womens consciousness groups, pools and tennis and racquetball courts, for which they pay handsomely, the Merrweather Post Pavilion, their own kiddie zoo and the Columbia Mall that attempts to recreate Main Street under glass.

Meanwhile, on the Walter and Paul Feaga Dairy farm west of Ellicot City, Barbara Feaga pauses from hanging the wash outside to reflect, "I think the people in Columbia are lonely. They have to look for things to entertain, to devote their spare time to People out here don't have any spare time.

"There is just a difference in their style of life an our style of life," she said. "The countians had their families here, they add an established social life, they had their church suppers."

Philosophically, said Feaga, "they're liberal and we're conservative. It's the approach of "the government owes me this." We'd just as soon the government leave us alone."

Barbara Feaga sat at a long picnic table under a huge shade tree while her husband baled hay. A few hours later, Ruth Keeton, the head of the County Council, reflected from the deck of her Columbia home that the new town "is a symbol of fast change that is hard to absorb. My own hope is for the county to become excited in fulfilling its different communities..."

the different communities fulfill themselves in their own way. While the cosmopolitan Columbians have an international food festival in July, the countians have the agricultural Howard County Fair, now in its 35th year, in August. Columbians attend the fair but mostly participate only as "fairgoers." There are no Columbians on the fair's board of directors.

"They don't have any farms, so they can't bring any livestock," said Allen T. Hill, the county fair's general manager. "They don't have fruit trees like in the rural area, so they don't bring jelly and jams. They bring baked good.

"If we try to put a mandatory set of values on each other," said Keeton, "it won't work."

When the rest of the council oppose what the countains want most - geographic districts to replace the present at-large system of representation.

The present system, its critics say, has resulted in a five-member council dominated by the more liberal, affluent, educated and urban-oriented Columbians who have seized power without sinking roots.

One of the critics is County Executive J. Hugh Nichols, a conservative Democrat who after an upset primary victory last fall joined with the council incumbents to run as "a great team for a great county."

Today, the team spirit is gone. Nichols is suing the County Council in a furious battle over footnotes added to the budget. The all-Democratic Council, which complained when Nichols hired an outside attorney and then got its own, has rejected several of the executive's nominations. Last week, the completely outcast and outnumbered Republicans, who view Nichols as a kindred soul, joined the fray with their own law suit against a Council-appointed charter revision commission that they say is illegally constituted.

Nicholas himself lives surrounded by Columbia in an "out-parcel" developed before new town visionary James Rouse could acquire it. In the heat of last year's campaign, the Columbia Flier, a trendy weekly that mirrors the new town's liberal chic, said Nichols has "associated himself with forces in this county that were out to destroy Columbia."

Nichols indeed writes a weekly column for the conservative old-line Howard County News, which is not widely read in Columbia. His opponents credit him with honesty and hard work, but it was the "countians" who helped him overcome a 65 percent margin of defeat in Columbia to win his seat.

In a county growing more than twice as fast as any other in the state - up from 36,152 in 1960 to an estimated 140,000 today - Nichols almost qualities as a "countian." A native of Alabama, he moved to Howard a decade before the first Columbians arrived in 1967. "I used to pick blueberries where the town center is," he says.

Sitting at his desk last week, handing Howard County buttons to a visitor, Nicholas asserted: : "The county has come a long way towards pulling together and removing the prejudices that existed four or five years abo."

In the hearts and minds of both Columbians and coutians, however, the resentments linger.

"I've never experienced the problems of bigotry as I have here," said a receptionist for the county who lives in Columbia. "There are a lot of negativisms," she said in a discernible New York accent. Affecting what whe considered a condescending tone, she said, "People here say, "Oh, you're from Columbia." "

Within the new town's boundaries, many countians feel, are more than Columbia's fair share of parks, pools and schools. The developers of the new town point out, however, that Columbia donated the land for schools and Columbians pay for their recreational amenities twice, through a special tax of 75 cents per $100 of assessed value and an annual user fee of $275 per family. Non-Columbians also are eligible, for a $445 annual fee.

The Columbia Association, which built and operates the facilities, nevertheless has run up a $42 million debt and has a projected operating deficit in 1980 of $400,000.

"I don't think people in Howard County understand what the Columbia Association is or even want to," said Mildred (Mickey) Dunham, Columbia's "ombudsman" to the community. "It's one of the biggest misunderstandings."

The misunderstandings are fed, both sides agree, by the limited person-to-person contact between Columbians and countians. Although some countians and Columbians serve together on official boards and commissions, many Columbians readily admit little interest in county affairs.

"I think of Columbia as my government," said one woman, whose husband works for the federal bureaucracy in the District of Columbia. "I go to Washington and back a lot," she said. "I don't really feel a part of the county."

The seat of county government is Ellicott City, a 200-year old mill town, sloping steeply towards the Patapsco River. It still looks like a village wrapped in time, a scene of rustic tranquility five miles from Columbia. Here, at least on the surface, the two cultures seem to gently blend, the boutiques and antique shops alternating with the old grocery stores selling local produce.

It is here, in a second-floor walkup on Main Street, that James K. Eagan III, president of the Columbian Democratic Club, has his law office.

"Most people in Columbia are oriented particularly towards Washington and are more interested in national and international, not local issues," said Eagan. "Columbians are a much more mobile, transient community."

Nonetheless, they vote at the local level - cohesively and in large numbers - and that has made Eagan a man to be reckoned with.

"Nobody paid any attention to us when there were 5,000 people in Columbia," he said. "Now that there are 50,000, it's different."

The first political shockwaves from the influx of new people came in 1972 when Columbia carried Howard County for George McGovern in the presidential primary. The rest of the 6th Congressional District went for George Wallace. In 1974, old countians were swept from office as three Columbians and two others of similar political bent won Council seats.

One of those ousted in the 1974 sweep was Ridgely Jones, a conservative countian whose family has farmed the same piece of land near Slacks Corner since 1774.

"When I was in office. Columbia felt it didn't have any representation, but it wasn't true," said Jones, 66. "Now people outside feel they have no representation. That's not necessarily true, either."

"We're all very accessible and open," said Ruth Keeton, who has been active in farmland preservation efforts and is considered a possible challenger to Rep. Beverly Byron, a conservative Democrat representing Western Maryland.

"Four years ago," Keeton said, "I met a woman five miles up the road who'd never been in Columbia, but I've been determined not to let it be a barrier in terms of communication."

Keeton acknowledges the schism and blames the developers of Columbia in part for its continuance. It is a view shared by many countians.

In the beginning, Keeton said, House representatives were everywhere selling their dream to the countians to win the rezoning to make it possible. "After Columbia began," she said, "I felt Rouse never quite kept that kind of education up."

Scott Ditch, Rouse vice-president for public affairs, was part of the early campaign to win county support. "The county was rural but suburbanizing rapidly," he said. "The whole premise of Columbia was that it not be an undue burden on the rest of the county, and that has been the case.

"There are a lot more similarities than differences," between Columbia and the rest of the county, Ditch said. He compared the differences to those "between Georgetown and Chevy Chase."

Out at Ridgeley Jones, place, the old farmer recalled the first wave of new people who filled several suburban subdivisions south of Baltimore after World War II."We, being older countians, had quite a few differences of opinions with the suburbanities," he recalled. "Gradually, we got to know them and it worked out."

If only the Columbians would sink roots, Helen Jones said, the same thing could happen again.

To some extent, the process is under way: Dr. James Jordan, the Columbia Medical Plan director who is from Macon, Ga., sold his Columbia home after five years for a six-acre property three miles away where, he said, "I felt more comfortable."

Many Columbians, said W. Wesley-McDonald, a 33-year old countian who sells real estate, "have a love-hate relationship with the place. After a while, some of them want to get away from the plastic and live in the country. As they say, some of my best friends are from Columbia." CAPTION: Picture 1, Modern architecture sets Columbia off from the surrounding county.; Picture 2, Westward view up main street in Ellicott City, county seat of Howard County which remains largely rural. By John McDonnell - The Washington Post; Map, no caption, By Dave Cook - The Washington Post; Picture 3, Parents and children relax around fountain in Columbia Mall. Few residents of Howard County shop at the mall. By Larry Morris - The Washington Post; Picture 4, J. HUGH NICHOLS...Howard County executive