Pat Muller and Peggy Hrubec did not consider canceling their sisterly shopping expedition this morning, just because their country had begun bombing Baghdad.

But now that the war has begun, Ms. Muller, 53, does plan to show Ms. Hrubec where all her important papers are before she goes to Las Vegas at month's end, ''in case the plane goes down or is sabotaged,'' she said. Ms. Hrubec, 48, said she would probably ''throw in an extra Mass this week.''

''There was this sense of foreboding,'' Ms. Muller said as the two women headed to celebrate her approaching birthday over lunch at Wildfire, a popular steakhouse where the 15-minute wait for a table was slightly shorter than usual. ''I wouldn't say there's more fear today. It's almost like, let's get it over with.''

The first day of the attack on Iraq unfolded as a mundane Thursday in much of the nation, as people struggled to balance celebrating the first signs of spring with a nagging sense that the mood should be somber.

They went to work, where coffee-break chatter was as likely to be about the opening round of the N.C.A.A. men's basketball tournament as about foreign policy. They went to class, where some walked out for the latest in a series of coordinated campus protests. They went to lunch, as televisions above the bar showing Iraq aglow with explosions and anti-aircraft fire.

''It feels like it should feel different,'' said Marci Oser, 29, as she turned a planned evacuation drill at her Chicago office building into a smoke break, ''but it doesn't.''

Many retail shops, restaurants, car dealerships and real-estate agencies reported fewer customers than usual throughout the day, particularly in New York, though the Mall of America outside Minneapolis was extracrowded, with scores of children on spring break riding the roller coaster. Wal-Mart saw spikes in sales of bottled water, canned meat and propane stoves. Reservations for Hertz rental cars were down and cancellations were up.

''I'm most worried about what's coming next,'' said Rozalind Brack, 65, the owner of Rozalind, a women's clothing store in Alexandria, Va. ''I don't think it's going to be too long before we're attacked again, which makes it hard to get people excited that pink is going to be the big color this spring.''

But even as the war's debut disrupted some business, economists were relieved to be free of some of the uncertainty that has been delaying the economic recovery. They expected companies to start making long-delayed decisions about hiring and ordering equipment.

David A. Daberko, chief executive of the National City Corporation, a bank with 1,100 branches in the Midwest, said some of his employees had decided to forgo the free trips to Florida they received as rewards.

''The real issue is not the war,'' Mr. Daberko said. ''It's terrorism and the effect the war will have on terrorism. That's what weighs on the minds of business people and consumers.''

What was weighing on the mind of Jim Anderson of Butte, Mont., was keeping track of the 15 cars full of friends and relatives who caravanned to Salt Lake City to watch Gonzaga University's basketball team beat Cincinnati, 74-69, at the Huntsman Center.

In the stands, Leah Felt, with a basketball brooch on her red sweater, chose to sit through the moment of silence before tipoff. ''I'm so angry about this war,'' Ms. Felt explained. Her daughter, Marion Felt, stood, saying, ''If we are going to fight, I am going to support the troops.''

March Madness took on new meaning in a split-screen nation.

At Wildfire, in the Oakbrook Shopping Center here in this suburb 25 miles west of Chicago, one television showed Marquette University beating Holy Cross while another showed Chicagoans talking about the war. At the Argosy Casino in Baton Rouge, La., patrons demanded, ''We want to watch the tournament!'' Eric Bornholdt, the bartender, switched 6 of his 12 televisions's to ESPN, but left the sound up on the news.

At Logan International Airport in Boston, Daniel Brooks, an accountant from Peoria, Ill., who stayed up late Wednesday watching news of the war, nursed a cup of clam chowder as he filled out an N.C.A.A. tournament bracket for a pool.

''I'm trying to pay as much attention to what's going on overseas,'' Mr. Brooks said as CNN appeared on the television over his left shoulder, ''but I have to call my buddy and let him know what my picks are.''

Barbara Karrman of Platteville, Wis., said she planned to do ''some channel flipping'' tonight.

''I have to support the troops,'' Ms. Karrman said while getting her hair done in Madison. ''I also have to support the Badgers.''

With war having been predicted for weeks, most people said today's events were simply the inevitable coming to pass. Many struggled to muster adequate interest. Others mourned the failure of diplomacy, worried about the potential loss of life and tried to quell their nerves.

In Laguna Beach, Calif., Anthony Rojas, a Navy reservist, shot hoops by the Pacific with his five sons, ages 3 to 12. ''We've been talking about the war most of the day,'' said Mr. Rojas, 34, who returned in October from a deployment in Bahrain and Kuwait. ''Basically, today, I just wanted to come to the beach and enjoy time with my kids. Because you never know. You just never know.''

In Dearborn, Mich., home to the nation's highest concentration of Muslim Arab Americans, Zeinab Abbas said her sister did not want to wear the traditional head scarf to school this morning. ''I don't feel American,'' said Ms. Abbas, 19, an American citizen. ''As soon as something happens like this, I am not looked at as an American.''

Here in Oak Book, Karen Bushy, the mayor, awoke this morning to find her pager on the fritz. Because of the war, she sent for a new one instead of waiting to have it fixed. The village sent an extra fire truck to a routine alarm at the shopping center, just in case.

''I just feel like the world is not the same place it was yesterday,'' said Ray Baker, 58, who worked his normal shift at a hospital but planned to go to the federal building in downtown Chicago this evening in search of an antiwar rally. ''I feel like I can no longer sit on the sidelines.''

Lee Nicosia, a middle school English teacher, took advantage of the power failure at her school to power-shop at Costco, but she said the war was definitely on her mind.

''Did I park myself in front of the TV and watch every little thing? No,'' she said. ''Will I turn on the TV as soon as I get home? Yes. Am I proud to be an American? Yes. Did I buy French wine? Hell, no.''
Wednesday night, Mrs. Nicosia, called her 21-year-old son, Joey, who lives in a Boston high-rise, and spoke also to his girlfriend, Lauren Kroll, who confessed that she was scared. Mrs. Nicosia recalled: ''She actually said to my son, which is so heart-breaking, 'Do you think we ought to go get canned goods?' ''