Authorities in the United States are investigating reports of Black people across the country receiving text messages invoking slavery following Donald Trump’s victory in the presidential election.

The racist text messages have been reported by people in more than a dozen US states, including California, Pennsylvania, New Jersey, Michigan, North Carolina, Virginia and Alabama.

The wording of the messages varies but follows the same basic script of telling the recipient they have been “selected to pick cotton at the nearest plantation”, according to local news reports and social media posts.

Some of the texts were labelled as coming from a “Trump supporter” or included the hashtag, #MAGA.

Frances Carmona, a Native American woman in Grand Rapids, Michigan, told local media that her 15-year-old niece had received one of the messages, which said she should be ready to be “searched and patted down once inside of the plantation”.

“Upset is an understatement,” Carmona was quoted as saying by NBC affiliate WOOD-TV.

“I don’t know what’s happening. I knew things were going to happen after the election, but not the day after. You know, it is kind of scary. It’s frightening.”

The FBI said on Thursday it was aware of the messages and was in contact with the Justice Department and other federal authorities.

“As always, we encourage members of the public to report threats of physical violence to local law enforcement authorities,” the agency said in a statement.

The Federal Communications Commission said it was investigating the texts in conjunction with federal and state law enforcement.

Attorneys general in a number of states also confirmed that they were looking into the matter.

“These messages are horrific, unacceptable, and will not be tolerated,” Maryland Attorney General Anthony Brown said.

“If you have been sent one of these texts, I am asking for you to please come forward and report it. I am committed to protecting the rights of all Marylanders. There is no home for hate in Maryland.”

The NAACP, one of the largest Black civil rights organisations in the US, condemned the messages.

“The threat – and the mention of slavery in 2024 – is not only deeply disturbing, but perpetuates a legacy of evil that dates back to before the Jim Crow era, and now seeks to prevent Black Americans from enjoying the same freedom to pursue life, liberty, and happiness,” NAACP president and CEO Derrick Johnson said.

“These actions are not normal. And we refuse to let them be normalised.”

The Southern Poverty Law Center (SPLC), another civil rights organisation, also expressed condemnation, describing the messages as a “public spectacle of hatred and racism that makes a mockery of our civil rights history”.

“Leaders at all levels must condemn anti-Black racism, in any form, whenever we see it – and we must follow our words with actions that advance racial justice and build an inclusive democracy where every person feels safe and welcome in their community,” Margaret Huang, SPLC president and CEO, said in a statement.

About one-fifth of the hate crimes reported in major US cities in 2022 were targeted against Black people, according to police data analysed by the Center for the Study of Hate and Extremism at California State University San Bernardino.