In what year did Iran and the US stop having diplomatic relations?

The year when Iran and the United States stopped having diplomatic relations is 1980. This dramatic shift in relations occurred after the Iranian Revolution of 1979, which resulted in the overthrow of the Shah, Mohammad Reza Pahlavi, a pro-Western monarch, and the establishment of the Islamic Republic led by Ayatollah Khomeini.

Following the revolution, the U.S. Embassy in Tehran was seized in November 1979, and fifty-two American diplomats and citizens were held hostage for 444 days. This event fundamentally altered the relationship between the two nations and ultimately led to the severing of diplomatic ties in April 1980. It marked a significant point in U.S.-Iran relations, transitioning from previous engagements to a state of enmity that persists today.

The other years are incorrect because, while tensions began to escalate in the mid-1970s, it was not until the hostages were taken and the formal breaking of relations occurred in 1980 that the diplomatic channels were definitively closed.