THE PRESS RAFT? That's a new thought, but then we live in times of rapid technological change. The press raft, as we understand it, preceded the White House staff raft, but followed the presidential flotilla on the journey down the Middle Fork of the Salmon River. By all accounts, even the most far-sighted political analyst could not see much from the press raft - except, of course, the Salmon River and the staff raft. The presidential raft preceded it at a considerable distance. But the press raft embodied the sound principle that wherever the president goes, there goes the press - vigilant, diligent, loud, quarrelsome and inevitable. The perquisites of the presidency are vast, but they do not include solitude.

The original idea was that President Carter would take a vacation in the wilderness. The track of the Salmon River was until recently wilderness, and will now be wilderness again, but the population densities in and around the presidential party must have been close to those on 16th Street at noon. Not to mention the heavy traffic in the air space at high attitude the military aircraft stuffed with communications equipment, and at low level the Marine helicopters doing taxi service. Private planes were excluded, but there were incursions, by one means of ground transportation or another, by the local papers, which were enraged at being excluded from the national press pools. Ah, wilderness.

In recent months we have observed a certain similarity of political atmosphere between the present period and the 1920s. It's a time of largely personal preoccupations, with few deeply felt public dangers and not many public issues of moral urgency. It's the kind of time in which it's hard for anybody to think of a reason why he shouldn't get out of town for a little while.

President Coolidge spent the entire summer of 1927 in the Black Hills of South Dakota. The executive offices were established in the school at Rapid City, an you can find the classic account of it in William Allen White's splendid biography, "Puritan in Babylon." The press entourage had not yet acquired its platoons of television technicians, all wired together for safe-keeping. But Mr. White recorded the procession of "heralds, newshawks, camera men . . ." surrounding Mr. Coolidge on the trip to the Black Hills. You may have seen the pictures of Mr. Carter in the life raft, sure-footed but life-jacketed, peering resolutely downstream. It could have been worse. In South Dakota, the natives presented Mr. Coolidge with a cowboy suit and a sombrero, in which he was duly photographed.

Mr. Coolidge's summer was not uneventful. On one occasion, he took a trip to Yellowstone Park to see the geysers but took his meals in his hotel room. He did not like being on public display. Mr. White says that the West, with its open ways, was offended.

It was from the Rapid City White House that Mr. Coolidge distributed to the press the famous 10-word announcement, "I do not choose to run for president in 1928." He explained to Sen. Arthur Capper of Kansas, who happened to be present, that, with his two years as vice president, a second term would have meant 10 years in Washington - and that was too long. Perhaps that is one point on which Mr. Carter would agree with him. Across half a century, they share that deep suspicion of Washington as a way of life. Mr. Carter represents, as Mr. Coolidge represented, the virtues of rural life to which this highly urban nation periodically turns.

But there are differences. One of them is that Mr. Coolidge went West in June and didn't return until autumn. Mr. Carter, who now proceeds to the Grand Tetons, is taking a conventional two weeks. The nights in the mountains are getting nippy, and there have been reports of snow flurries. Two weeks in the wilderness will not be too short a vacation, as we understand it, for the press raft.