It is make your mind up time for America. A hopeful, incrementally better, boats-against-the-current United States; or a US flirting with a dystopia from the pen of a Stephen King or Cormac McCarthy? A serious but flawed Democratic candidate; or a Republican whose election would be the sum of all fears? That’s the choice, the only choice, on offer.

If we had a vote, we would use it to elect Hillary Clinton as president on Tuesday. She has a thoughtful and ambitious policy agenda for America’s inequalities and injustices. She has an internationalist outlook. She has responded to concerns about her cautious centrism by committing to more radical plans. She is eminently prepared and qualified for the job. She is a fitting successor to Barack Obama. And it is high time there was a woman president.

To these can now be added the fact that, as of Sunday, she is no longer under investigation. The announcement, just over a week before polling, that a new batch of emails was being investigated was, at best, an extraordinary misjudgment by the FBI director James Comey. It triggered nine days that needlessly shook US politics, narrowed the polls and may have shaped the election. Now the bureau has said Mrs Clinton will face no further investigation or charges over her use of a private email server. Mrs Clinton bears a share of responsibility for bringing this storm on herself. But the essential fact is that she is in the clear.

The thing that stares Americans in the face on a close-fought election day, however, is that the only alternative to Mrs Clinton is Donald Trump. It needs to be said again, at this fateful moment, that Mr Trump is not a fit and proper person for the presidency. He is an irascible egomaniac. He is uninterested in the world. He has fought a campaign of abuse and nastiness, riddled with racism and misogyny. He offers slogans, not a programme. He propagates lies, ignorance and prejudice. He brings no sensibility to the contest except boundless self-admiration. He panders to everything that is worst in human nature and spurns all that is best.

Mrs Clinton is far from perfect. But Mr Trump plumbs the depths of imperfection in ways that have no precedent in frontline modern American politics. All countries from time to time produce leaders who are ignorant or vain or who lack intellectual judgment or personal grace. But Mr Trump is the first candidate to get so close to power who has no experience of the practicalities of politics and government, and who does not seem to care about them either. If he is elected president it will send the worst possible message to America about itself, and an even worse one to the rest of the world.

There are three particular ways in which electing Mr Trump is a step that should be spurned by any responsible American voter. First, it would mean a rightwing president governing with a rightwing Congress. Mr Trump and the Republican establishment have many differences, but they would find no difficulty cutting taxes for the richest or sparking an aggressive trade war with former partners. They would ensure, as a priority, that the conservative majority is restored on the supreme court. Progress on civil rights and equality would be thrown into reverse. Abortion rights would be under threat.

Second, Mr Trump’s election would be, and would be seen as, a victory for white America over African, Hispanic, Asian and other American ethnic groups. In this campaign Mr Trump has campaigned against migrants, insulted Muslims, stereotyped black people and disrespected Mr Obama at every turn. He has been backed by every white racist in the land. Race remains America’s deep foundation sin, and Mr Trump will deepen it.

Finally, electing Mr Trump will make the world an even less safe place. It will threaten US commitment to international institutions, including the UN, and support for international norms. It will contribute to instability and set back efforts to solve environmental problems. It will encourage autocratic leaders in places like Russia, China, Turkey, North Korea and elsewhere. It makes the nurturing of the planet more difficult and the future of the human race more uncertain.

For all these reasons, Americans should summon a special level of seriousness and display a profound responsibility when they go to the polls. Anything other than a vote for Mrs Clinton is a vote for conservatism off the leash, a deepened racial divide and a more dangerous planet. The time for messing is over. America deserves much better than Mr Trump. So does the world. Mrs Clinton is much better. So elect her.