Transportation sector CO2 emissions worldwide 1990-2020, by country

For more than three decades the United States has produced more carbon dioxide emissions from transportation than any other country. In 2020, U.S transportation emissions plummeted roughly 12 percent to 1.56 billion metric tons (GtCO2). This substantial reduction was a result of COVID-19 related lockdowns and travel restrictions.
The European Union was the second-largest contributor to global transportation emissions up until 2018, but in 2019 it dropped below China. Transportation emissions in China have soared over the past two decades and in 2020 climbed to a peak of 966 MtCO2. Unlike in other major economies, transportation emissions in China actually increased in 2020.