To understand why Narendra Modi will almost certainly be India's next prime minister when the vote tally is announced Friday, the best place to visit is Uttar Pradesh. It's a sprawling state with 200 million people whose 80 parliamentary seats account for nearly one in seven in the lower house of Parliament. Mr. Modi is running for Parliament from Varanasi, an ancient temple town in the poor and populous eastern part of the state.
Here, up four flights of grimy stairs, in a building where the power cuts can be longer than periods of actual power supply, sits a symbol of India's aspiration and frustration: a somewhat oddly named English-teaching academy called T-Trounce. The students—mostly 18-28-year-olds in college or in their first jobs—aren't privileged enough to speak the language of India's ruling elites fluently. But they're ambitious enough to want to better themselves. When asked, nearly four-fifths of them in a class of 50 students said they were voting for Mr. Modi.
"India will shine all over the world," said Manish Pandey, an unemployed 24-year-old software programmer. "The economic level is going to increase. The per capita income level is also going to increase."
If the exit polls are right, many Indians share Mr. Pandey's optimistic view of Mr. Modi's powers to rejuvenate. The Center for the Study of Developing Societies estimates that the BJP alone could win as many as 242 seats in the 543-seat lower house of Parliament, its best ever performance. Along with its allies, the opposition party is predicted to win about 276 seats, enough to comfortably form a government. Several smaller regional parties will likely bolster the winning coalition's numbers by pledging their support.
In Uttar Pradesh alone, the BJP may win upward of 50 seats, its best showing in nearly two decades. Meanwhile, the ruling Congress Party, battered by corruption scandals, slowing economic growth and lackluster leadership, is expected to crash to an all-time low of 72-82 seats nationwide.
By now it has become a cliché to describe India's election as the most polarizing in the country's history. This is partly true—for India's left-leaning liberals and many Muslims, Mr. Modi is Enemy No. 1 for failing to prevent gruesome anti-Muslim riots on his watch in 2002 after a Muslim mob attacked a train carrying Hindu pilgrims and killed 59 people. More than 1,000 people died in the riots, three-fourths of them Muslim. And though a Supreme Court-ordered investigation said Mr. Modi wasn't legally culpable for the violence, for India's commentariat the political fault lines they created have not disappeared.
But step away from the hothouse atmosphere of Delhi's intellectual salons and a different picture emerges. For voters like Mr. Pandey, these elections are not remotely about either fear or anger. They're overwhelmingly about hope for a better future. India's youngest voters prefer Mr. Modi to his nearest rival, Congress Party Vice President Rahul Gandhi, by a margin of more than two-to-one.
In many ways, the BJP's likely victory is a triumph of messaging. Economists and journalists parse data in interminable arguments about Mr. Modi's so-called Gujarat model of development. At T-Trounce, stripped of all nuance, Mr. Modi has decisively won the argument.
Most students see Gujarat as shorthand for smooth roads, reliable power supply, safety for women and private-sector jobs. Some have visited the state themselves; others have friends or relatives who have visited. Some have made up their minds after viewing pictures of the state's superior public works on Facebook.
What does this surge of optimism mean for India? While it's too early to say whether a new government will be able to restore India to the double-digit growth rates it enjoyed as recently as three years ago, there's no question that in the broadest possible sense Indian politics has taken a turn in the right direction.
The old fault lines of caste and region haven't disappeared, nor has a religious divide between Hindus and Muslims. But for the first time, large numbers of Indians are willing to transcend them. For instance, Mr. Pandey, the unemployed software engineer with broken English, is a Brahmin. For his grandparents, voting for a so-called lower-caste politician like Mr. Modi would have been anathema. For Mr. Pandey it's irrelevant.
Similarly, the BJP has broken out of its regional strongholds in northern and western India by making inroads in the south and east. Thanks in large part to Mr. Modi, it has also expanded its support among rural and lower-caste voters.
The new prime minister will have his work cut out for him. The jury remains out on whether he can privatize loss-making state-owned companies, revitalize a sagging banking sector, win back the confidence of foreign investors scarred by policy flip-flops, and spur a manufacturing renaissance that channels the pent up aspirations of India's young population toward productive jobs.
But for now, at least, one thing is clear: The BJP's likely mandate is a mandate for development. That fact, and the political changes that flow from it, are hopeful signs for the future.
Mr. Dhume is a resident fellow at the American Enterprise Institute and a columnist for WSJ.com. He tweets @dhume.