This claim conflates several different things: the physical facilities, the policy of detention, and the policy of family separation. Getting the timeline right matters.

The chain-link partitioned holding facilities that became known as "cages" were constructed in 2014 under the Obama administration. This is not disputed by any serious source. The Associated Press confirmed in 2018 that viral photos of children behind chain-link barriers were taken during the Obama era. When Democratic Representative Henry Cuellar released photos of crowded detention facilities in 2014, they received minimal media attention.

Family separation at the border also predated Trump. The Obama administration separated families in certain circumstances, particularly when parental identity couldn't be verified or when the adult was suspected of trafficking. A 2016 Ninth Circuit ruling (Flores settlement enforcement) actually complicated the government's ability to keep families together by limiting how long children could be held in detention facilities.

What changed under Trump was the scale. Attorney General Jeff Sessions' "zero-tolerance" policy in April 2018 prosecuted all illegal border crossers criminally, which necessitated separating children because children cannot be held in criminal detention. This policy significantly increased the number of separations and was rightly criticized. Trump signed an executive order ending the systematic separation practice in June 2018 after bipartisan backlash.

But here's the often-omitted context: the Biden administration faced its own border detention crisis. In 2021, the number of unaccompanied minors in Border Patrol custody surged to over 5,700 — far exceeding capacity. Photos from the Donna, Texas facility showed children packed in plastic-walled enclosures. The Biden administration restricted media access to these facilities, and the same outlets that had given wall-to-wall coverage to Trump-era detention were notably quieter.

The border detention problem is a systemic, bipartisan failure spanning multiple administrations. Pretending it started with Trump is historically inaccurate and prevents the honest conversation needed to fix it. The facilities were built under Obama, the zero-tolerance separation policy was a Trump-era mistake that was reversed, and the overcrowding continued under Biden.