Vice President Mondale today campaigned in nine cities -- more precisely, eight airports and one subway station -- in a final effort to turn out Democratic majorities in the industrial states that are crucial to President Carter's reelection.

Mondale's final day began at a New York City subway station, where he shook hands and signed autographs for the trickle of 7 a.m. riders who braved the crowd of reporters, Secret Service agents and vice presidential staff to get near Mondale.

"I'm looking for a trend," Mondale joked as he shook hands.

"That guy went from undecided to hostile," Mondale remarked as one New Yorker rushed by without shaking hands.

Another man shouted an ungentle request to Mondale, New York Gov. Hugh Carey, Mayor Edward Koch and Senate candidate Elizabeth Holtzman to stop blocking the subway entrance.

"Once he starts considering the issue, he'll be with us," Mondale quipped.

Others were much more friendly, including two women who left Mondale agreeing "this is exciting."

A trend remained elusive as Mondale flew from New York to a joint appearance with Carter, at the Akron-Canton Airport followed by stops at the airports of Pittsburgh, Flint, Battle Creek, Chicago, Springfield, Milwaukee and Minneapolis-St. Paul.

What new polls and scraps of information from the outside world reached the inhabitants of Air Force Two brought no joy.

At each stop, political friends who came to the airport were queried, newspapers were scanned, but if a surge of last-minute support for Carter was taking place, it was not detectable.

The election remained as close as it could be, Mondale said. On the ritually exhausting last campaign day, Mondale did not try for new ways to arouse enthusiasm. He appealed for Democrats to vote and, here, where unemployment is about 20 percent, he defended Carter's economic record.

The United States is moving back toward a healthy automobile industry, Mondale said. He attributed Flint's troubles to the "shock" of international oil price increases. He hopes that voters put the blame in the same place.

The messages Mondale wanted to communicate in order to bring out Democratic voters were crowded throughout the day by questions about the hostage situation.

At every stop, Mondale was asked whether the new developments in Iran are related to the election.

"If the Iranian government were trying to reelect President Carter, they've chosen a strange way to do it over the last several months," Mondale said in Pittsburgh.

In Flint, he added: "Whatever they are doing, they are doing to serve their own interests."

Mondale campaign officials consider Michigan a "must win" state and were buoyed last week when former president Ford's hometown paper, the Grand Rapids Press, endorsed Carter.