Donald Trump speaks at the Republican National Convention in Cleveland, July 21. (Jonathan Ernst/Reuters)

Donald Trump’s speech Thursday night at the Republican National Convention was notable for its tone. As my Post colleagues Philip Rucker and David Fahrentold put it, “Donald Trump painted a dire portrait of a lawless, terrorized nation.” How dire? Consider this: Trump’s speech was the most negative in tone of any convention acceptance speech since 1972.

That is the conclusion of a new analysis by McGill University PhD student Denver McNeney. He measured the tone of each speech by analyzing its content using Lexicoder. This software compares a text to a dictionary of about 4,500 words and phrases that have been categorized as either positive or negative. This provides a sense of whether the text contains more positive or more negative words.

For example, McNeney gave me this example from Trump’s speech: “Any government that fails to do so is a government unworthy to lead.” The software would consider both unworthy and fails to be negative.

Here is McNeney’s graph:

Graph by Denver McNeney

The graphs shows the tone of each speech over its duration. Almost never are acceptance speeches more negative than positive at any point during the speech.

By contrast, Trump’s was almost entirely more negative than positive, and it remained that way for the majority of the speech. Only toward the end did the tone become more positive, but even then the speech was far less positive than any other. The contrast with Romney’s is particularly striking.

A dire portrait, indeed.