Painted in oil in 1985, Dixie Red Seville belongs to the last moment of the luminous sky paintings, just before his turn towards darker grounds, or Nocturnes, and to the blank “censor” bars that replace words altogether. Here, a twilight sky fills the whole surface, from a deep indigo band at the top, through streaks of blue and a plum coloured bank of cloud, to a pale, almost creamy glow along the lower edge. The brushwork runs in long horizontal strokes, so that the sky seems less observed than glimpsed at speed. Hal Foster’s remark that “the windscreen is indeed the unseen frame” of many of Ruscha’s pictures finds a particularly apt illustration here.

Across this sky, five words in Boy Scout Utility Modern - the type face that the artist designed in the early 1980s - are distributed in two colours. In red, descending diagonally from the upper left: DIXIE, RED, SEVILLE. In dark navy, slightly offset to the right: VEGAS, PLATES. The two sequences interlock, letter crossing letter, so that the eye hesitates between reading by line and reading by colour. The red itself is modulated by the light: rusty and almost absorbed into the cloud in DIXIE, it brightens to vermilion and orange as it descends into the glow of the horizon.

Read by colour, the phrase becomes a description, the kind relayed over a police radio: a Dixie red Seville with Vegas plates. Dave Hickey, who discussed the painting in Parkett in 1988, heard precisely this “police-band urgency”. Beneath the euphony of the words he detected “a vehicle in cognitive as well as narrative transit”, one “named for one location (Seville), painted a colour named for another (Dixie) and licensed in yet a third (Las Vegas)”.

Each word opens a geography. Dixie names the American South, a word of song and nostalgia, close to the Oklahoma of Ruscha’s youth. Seville names the Andalusian city of Velázquez and Murillo, but also, since 1975, Cadillac’s most exclusive model, the smallest and most expensive car in its range, conceived to rival European luxury imports. In 1985 the Seville was in the last year of its distinctive “bustleback” design. A Spanish city had become an American product, exactly the operation Ruscha describes when he says that “Hollywood” is like a verb: “You can take something in Grand Rapids, Michigan and ‘Hollywoodize’ it. They do it with automobiles.”

Having built a desert retreat in the Mojave near Joshua Tree, completed in 1981, he began to set his phrases against vast horizons, sunsets and banks of cloud. The widescreen canvases he called Grand Horizontals are cinemascopic in proportion, with skies of saturated colour that evoke studio backdrops as much as nature.

These skies carry an art historical memory. Critics have related them to the Hudson River School, to Thomas Cole and to his pupil Frederic Edwin Church, and to the Western panoramas of Albert Bierstadt, painters who made the American sky a theatre of the sublime. Ruscha keeps the grandeur but empties it of its Romantic sermon. “A lot of my paintings are anonymous backdrops for the drama of words”, he has said. “In a way they’re words in front of the old Paramount mountain peak.”