In some cases, competing firms can handle only a small portion of the freight handled by the 22 firms. United Parcel Service, for example, is prepared to handle more business but can move shipments of only 150 pounds or less, a spokesman said.
Talks broke off last week between the International Brotherhood of Teamsters and Trucking Management Inc., which represents the trucking firms in labor negotiations, after the union rejected what the companies described as their last offer. The Teamsters said company proposals to allow greater use of part-time workers and railroads would eventually lead to lower starting pay and job losses.
The unionized companies, which face stiff competition from fast-growing non-union firms with lower costs, say the proposals are necessary to ensure their long-term survival.
On Wednesday, Trucking Management agreed to let many of its smaller members sign interim agreements with the Teamsters to allow them to continue operating during the strike. Those firms, which operate primarily on the East Coast and employ about 10,000 Teamsters, would adopt the terms of a contract when one is reached.
In Southern California, which is home to an estimated 7,000 to 10,000 union members affected by the strike, Teamster picket lines formed outside about 100 terminals.
Sympathetic drivers honked their truck and car horns as they passed about 25 strikers peacefully walking a picket line in front of the Yellow Freight System and CF terminals on East Washington Boulevard in Los Angeles early Wednesday afternoon.
Management proposals to hire more part-time workers seemed to be the strongest factor prompting the Teamsters to picket.
"They just want to increase their profits and turn this into a part-time industry," said Zack Lopez, a local driver for Yellow who has been hauling freight for the company for 27 years.
In Pacoima, Teamster Kelly Price worried about the strike's impact on his family. Price and his wife, Annette, are expecting their third child. He said a long strike would hurt his family.
"We will have to dip into our savings, but that would last for about two months," said Price, who was picketing in front of Roadway Express Inc. "But I will not cross the picket line."
The first day of the strike found many companies shifting to other carriers to avoid disruptions.
"The potential for a negative impact on inventory increases the longer the strike lasts," said Laura Melillo, spokeswoman for R. H. Macy & Co., operator of the Bullock's and I. Magnin chains.
Macy, like many other retailers, has a lean inventory system, which gives store operators the flexibility to quickly change product mix. However, anticipating a possible strike, Macy ordered and received much of its spring line of clothing earlier than usual, Melillo said.
Wal-Mart, the nation's largest retailer, was also prepared for the strike.
"The company had selected alternative carriers as backups for the small percentage of our carriers who are Teamsters," said Jane Arend, a Wal-Mart spokeswoman.
Operations at the nation's Big Three auto manufacturers, while not immediately affected by the walkout, could be disrupted if the strike lasts beyond this week.
The reasons: Auto makers increasingly depend on outside suppliers for parts and components; they are using just-in-time inventory controls that reduce manufacturing costs but leave plants with few spare parts, and high demand for cars and trucks has plants operating at capacity, using parts on hand quickly.
Chrysler Corp. could be the most vulnerable to a prolonged Teamster walkout because it relies on outside suppliers for 70% of its parts. Its factories are running full tilt to meet the record demand for its vehicles.
"We are looking at some alternatives to deal with a strike of short duration," Chrysler spokesman Lee Sechler said.
A trucking strike in 1979, when the Teamsters were far more powerful, ended up crippling the auto industry with a walkout-turned-lockout that lasted 10 days. The cutoff in freight service prompted General Motors to lay off 12,400 workers. The Chrysler Corp. shut down almost completely, closing nine of its 10 North American auto assembly plants.
The 300,000 truck drivers and warehouse workers affected by that dispute went back to work after a settlement was reached providing 30% increases in wages and benefits over three years.
Times staff writers James M. Gomez and Debora Vrana in Orange County; Bettina Boxall, Stuart Silverstein and George White in Los Angeles; Chau Lam in the San Fernando Valley, and Donald Nauss in Detroit contributed to this story.