Donald Trump’s data purge has begun 

Key resources for environmental data and public health have already been taken down from federal websites, and more could soon vanish as the Trump administration works to scrap anything that has to do with climate change, racial equity, or gender identity.

Warnings floated on social media Friday about an impending purge at the Centers for Disease Control and Prevention (CDC), spurring calls to save as much data as soon as possible. The CDC shares data on a wide range of topics, from chronic diseases to traffic injuries, tobacco use, vaccinations, and pregnancies in the US — and it’s just one of the agencies in the crosshairs.

The CDC’s main data portal, which housed much of those datasets, was offline by Friday night. “Data.CDC.gov is temporarily offline in order to comply with Executive Order 14168 Defending Women From Gender Ideology Extremism and Restoring Biological Truth to the Federal Government” a notice on the webpage says, adding that it will become available again once it’s “in compliance” with the executive order.

Fortunately, researchers have been archiving government websites for months. This is typical with every change in administration, but there was even more imperative with the return of Donald Trump to office. Access to as much as 20 percent of the Environmental Protection Agency’s website was removed during the first round of Trump’s deregulatory spree. And now, it seems, similar moves are happening fast.

The CDC’s social vulnerability index and environmental justice index — tools that could show whether particular populations might face disproportionate health risks — have both been taken offline within the past week. In 2007, during the Bush administration, social scientists, geographers, and statisticians started developing the social vulnerability index (SVI), which incorporated demographic and socioeconomic factors including poverty, race, and ethnicity over the years.

The Biden administration launched the environmental justice index (EJI) in 2022. “Too many communities across our nation, particularly low-income communities and communities of color, continue to bear the brunt of pollution. Meeting the needs of these communities requires our focused attention and we will use the Environmental Justice Index to do just that,” then Health and Human Services Secretary Xavier Becerra said in a press release at the time.

Since stepping into office, Trump has tried to undo previous administrations’ work to address health disparities when it comes to race and gender. In an executive order Trump signed to undo Biden-era policies, the president wrote that “diversity, equity, and inclusion” (DEI) has “corrupted” government institutions.

He also claimed that “climate extremism has exploded inflation and overburdened businesses with regulation.” During his first term in office, there was a near 40 percent decline in the term “climate change” across websites for federal environmental agencies. It’s too soon to know what the damage might be this time around, but some webpages have already vanished. The US Department of Transportation’s “priorities” website has removed pages on both “climate and sustainability” and “equity.” It follows an internal memo sent this week instructing USDOT operating administrations to identify and ultimately “terminate” Biden-era activities relating to climate change and DEI.

Donald Trump’s efforts to limit foreign aid seem to have also led to information being taken down on HIV and AIDS. The data webpage for the US President’s Emergency Plan for Aids Relief (PEPFAR) was taken down this week. PEPFAR has been around since 2003 and helped more than 20.6 million people get access to antiretroviral therapy in 2024 alone, according to a snapshot of the website taken by the Wayback Machine on January 26th, before it was taken down.

The End of Term Web Archive project has saved content on federal government websites during every presidential transition since 2008. The Environmental Data and Governance Initiative (EDGI) that formed after Trump was first elected also documents changes to government websites and works to make archived datasets available elsewhere. It has backed up data from the CDC’s Social Vulnerability Index and Environmental Justice Index and shared it on a webpage for The Public Environmental Data Project.

Yet even if these datasets have been archived, they aren’t as helpful when they aren’t updated. “Any dataset has a lifespan of utility,” says Dan Pisut, senior principal engineer at GIS software company Esri.

Aging datasets might not fully represent what’s actually happening on the ground, so people have to be careful about how they use them, Pisut points out. It could be risky, he says, but “better than nothing.”

Update, February 1st: This post has been updated with information about data.cdc.gov going offline.

Update, February 5th: Data.cdc.gov is now back online with a notice that says, “CDC’s website is being modified to comply with President Trump’s Executive Orders.”