Phoenix ? In 1948, when Arizona had been a state for just 36 years and its population was only 700,000, it voted for President Truman. However, for several subsequent decades the face of Arizona politics was the leathery, suntanned Southwesternness of Barry Goldwater, the leading conservative politician between the death of Ohio’s Republican Sen. Robert Taft in 1953 and the rise of Ronald Reagan, a rise resulting partly from his participation in Goldwater’s 1964 presidential campaign. Arizona was the only state to vote Republican in 11 consecutive elections after 1948, until it voted for Bill Clinton’s 1996 re-election.

It is not novel that the outcome of this November’s presidential vote is expected to be closely contested in only about 18 states. It is novel that Arizona is one of the 18.

In 2000, George W. Bush carried Arizona, which then had a Republican governor, with just 51 percent of the vote. Referring to the red (Bush) and blue (Gore) states on the map of the 2000 election results, Janet Napolitano, 46, a Democrat elected governor in 2002, says Arizona is “red with tinges of blue starting to seep through.” Indeed, Democrats have won half of the last eight gubernatorial elections.

When it is said that the outcomes in this November’s presidential voting are considered predictable in about 32 states, what this means is that if many of those vote other than as expected, the election will be a landslide, in one direction or the other. If, however, you assume, as both campaigns do, that the nation remains as it was in November 2000, when five states were decided by less than 1 percent of the vote, and 18 by 6 percent or less, then three states are generally considered particularly pivotal. Florida, because it is emblematic of conditions in the last election. And Missouri and Ohio because they almost always are indicative: Since 1900, in 24 of the previous 26 elections they have voted with the winner. And no Republican has been elected president without carrying Ohio.

But, then, since the state’s founding, no Republican has been elected without carrying Arizona. There are now 5.3 million Arizonans wielding 10 electoral votes, two more than in 2000. Republicans still have a 6-point registration advantage. But independents are 23 percent of the electorate, and every two years since 1996, the rate of voting by Arizona Hispanics has increased.

Arizonans who welcome the growth of their state’s population — those who don’t should pack up and skedaddle; the pell-mell growth continues — should thank, among other things, their big neighbor. Asked why her state is growing so fast — 40 percent in the 1990s, faster than any state except Nevada — Napolitano answers with one word: “California.”

There is, of course, more to it than that. New Arizonans include retirees fleeing the winters of the upper Midwest and job-seekers drawn to the state that ranks seventh among recipients of defense spending. But begin with what Napolitano, wonderfully undiplomatic, calls California’s “crummy conditions.” Even earning $75,000, she says, “you still can’t afford a house most places over there.”

However, migrants bring with them aspects of “over there,” so: Is Arizona becoming, politically, more like California — more liberal? It has conservative policies, such as low taxes and considerable school choice. Twenty percent of its schools, the nation’s highest percentage, are charter schools. And Napolitano says that although her state is struggling with a $1 billion hole in a $6.5 billion budget, fiscal 2004 revenues rose 9 percent over 2003, and are expected to be up another 7 percent in 2005.

Yet if liberalism and urbanism still increase in tandem, a salient fact may be that Arizona is heavily and increasingly urban: Almost 80 percent of Arizonans live in or around Phoenix and Tucson. Mesa is a “suburb” contiguous to Phoenix, but its population is larger than that of St. Louis. And another fact encouraging to John Kerry is that the state has, Napolitano says, 600,000 veterans, with a large number from among Hispanic and Native American voters.

Like 51 percent of her constituents, Napolitano, Arizona’s second consecutive female governor (no other state has done that), is from elsewhere — born in New York City, raised in Pittsburgh and Albuquerque, educated in California. When asked if George W. Bush has an advantage because he is a Southwesterner, she laughingly replies: “He’s a Texan — that’s different.”

She says what one expects her to say: Kerry can carry the state, but “he’s got to come.” He will, often.

George Will is a columnist for Washington Post Writers Group.