Color the new online insurance marketplaces Blue.

On the first day that people could buy coverage under the federal health care law last week, the chief executive of Independence Blue Cross in Philadelphia had just learned that his company’s plans were the area’s least expensive available through the new state exchanges. “We were thrilled,” said Daniel J. Hilferty, the nonprofit insurer’s chief executive.

A 36-year-old can buy a so-called silver policy — a midrange plan — for $246 a month, not including the federal subsidies that could lower the cost even further. Out-of-pocket costs would vary, depending on the choice of hospital and doctor.

While other brand-name insurers like UnitedHealth Group, Aetna and Cigna are selling coverage only sporadically on the exchanges, consumers will find local nonprofit Blue Cross and Blue Shield plans in nearly every state and market in much the same way they did before the federal health law was enacted.

WellPoint, which became one of the nation’s largest insurers by combining more than a dozen Blue Cross plans into a profit-making company, is also actively participating in the exchanges in all 14 states where it operates. “We expect to be a strong competitor in most regions because our brand and local market experience are meaningful differentiating factors,” the company’s chief executive, Joseph R. Swedish, recently told investors.