The whole world knows that Donald Trump is on a mission to “make America great again.” But it’s unclear exactly when Trump thinks America was great. What era in this country’s history does he feel nostalgic about? To whence does he wish to return?

In the campaign video below, Trump claims that US infrastructure has made the country a global laughingstock. “Our airports, our bridges, our roadways. It’s falling apart, it’s a terrible thing to see,” he says.

If it is strong infrastructure for which Trump yearns, perhaps he wants to go back to the New Deal of the 1930s, when many of the country’s current bridges, roads, and airports were built.

1930s America

This was certainly a great decade for building in America. President Franklin Roosevelt’s Public Works Administration, created in 1933 as part of the New Deal, spent $3.3 billion on 651,000 miles of highway, 124,000 bridges, 1,000 miles of airport runways, and 84,000 miles of drainage pipes, among other achievements.

Of course, the New Deal was created in response to the Great Depression. In 1933, the US faced a 25% unemployment rate. Thousands of banks failed during the depression, and many people lost their homes and were forced to take shelter in tent cities. Let’s not forget the dust storms that caused severe droughts and destroyed farming throughout much of the US during the 1930s. So despite the era’s dedication to infrastructure, it’s unlikely to be Trump’s utopia.

1940s America

Could it be the 1940s, a time of great nationalism, that tickles Trumps fancy? Probably not. This was the decade in which the US was attacked by Japan at Pearl Harbor, sent millions of Americans abroad to face the atrocities of the Second World War, and deployed two atomic bombs. The country also sent 110,000 Japanese and Japanese-American residents to internment camps.

In addition, Americans faced strict rations on food, gas, shoes, and household appliances, and citizens were asked to donate spare rubber, scrap metal, paper and even cooking fats to aid the war effort. A lot of Americans took pride in this self-sacrifice, but few modern types are itching to go back.

1950s America

At first glance, this would seem to a more plausible golden era: A time of massive economic growth and great cultural icons such as Elvis Presley and Marilyn Monroe.

But as the US came into its own as a capitalist nation, the country was plagued by fear. McCarthyism created a paranoid witch-hunt for Communists, and there was genuine concern, as the Cold War arms race grew, that Russia would launch a nuclear attack against the US. Then there was the Korean War, which led to the deaths of 36,900 Americans.

On the home front, the 1950s were a time of segregation, racism and rampant sexism. Martin Luther King, Jr., Malcolm X, and Rosa Parks became prominent figures during this era. But the laws that denied African-Americans the same basic rights and opportunities as white people stayed in place throughout the decade. The 1950s are nothing to be nostalgic about. That said, given that Trump recently hedged on his opinion of white supremacists after initially disavowing a vote of support from former Ku Klux Klan leader David Duke, perhaps the 1950s’ legacy of hate wouldn’t be a problem for him.

1960s America

On one hand, the 1960s boasted hippies, sexual liberation, rock and roll and space exploration. And who doesn’t enjoy peace and love?

Then again, there was the Vietnam War, which divided the country politically and killed three million people, including 58,000 Americans. President John F. Kennedy was assassinated. Despite the passage of the Civil Rights Act of 1964, black Americans continued to struggle against discrimination and violence. Both Malcolm X and Martin Luther King, Jr., were assassinated. And widespread homophobia culminated in the 1969 Stonewall riots.

1970s America

After president Richard Nixon’s Watergate scandal and subsequent coverup was exposed, he became the first chief to resign in office. The Vietnam War dragged on. The US invaded Cambodia in 1970.

The fight for women’s rights gained strength, but a 1972 equal rights amendment stating that rights “shall not be denied or abridged by the United States or any state on account of sex” failed to win necessary ratification. Roe vs. Wade passed in 1973, but the Congress cut off funding for nearly all abortions in 1976.

1980s America

There are certainly some aspects of the 1980s that Trump probably finds comfortingly familiar. President Ronald Reagan came to power with his promise to “make America great again.” (Reagan didn’t specify which previous era of greatness he was referring to either.)

The decade was largely a period of wealth, conservatism, and yuppie culture. It could well be Trump’s favorite decade; the man himself rose to prominence in the 1980s. But then again, the early 1980s included a recession and 11% unemployment in 1982. The Reagan administration was caught selling weapons to Iran. And the federal budget deficit increased to nearly $3 trillion, around three times greater than in the previous 80 years.

1990s America

Who doesn’t feel nostalgia for the 1990s? It was a time when crime dramatically fell, household income grew and stocks quadrupled in value. Plus, US citizens were kept entertained by advances in technology and by President Bill Clinton’s impeachment in 1998.

But while the 1990s were the longest period of expansion in US history, it seems unlikely that Trump could really be harkening to the Clinton era as the golden age of America.

2000s America

The decade was overshadowed and defined by the terrorist attacks of September 11, 2001. Al Quaeda’s attacks on the World Trade Center and the Pentagon led to massive increases in national surveillance and security in a bid to fight the “War on Terror.” In response to 9/11, the US bombed Iraq in 2003, beginning a war that lasted eight years, caused the deaths of half a million Iraqis, and led to political instability that continues to exist today.

The other major US event of the decade was the Great Recession starting in 2007. It saw the housing bubble burst and Americans lose trillions of dollars in household wealth.

2010s America

This brings us to our current decade and Trump’s promises to make America great again. Certainly there are some aspects of the past that seem enviable in retrospect—the price of a New York apartment, for example. But the search for America’s era of “greatness” is an elusive one. The US has never experienced a period that embodied all of its best values without war, economic depression or tragedy. And even if there was a bygone era in which America had been truly great, Trump would be an unlikely candidate to recreate such a utopia.