One of Trump's central campaign promises was to build a 1,000-mile (1,600 km) border wall to Mexico and have Mexico pay for it.[327] By the end of his term, the U.S. had built "40 miles [64 km] of new primary wall and 33 miles [53 km] of secondary wall" in locations where there had been no barriers and 365 miles (587 km) of primary or secondary border fencing replacing dilapidated or outdated barriers.[328]
In 2018, Trump refused to extend government funding unless Congress allocated $5.6 billion in funds for the border wall,[329] resulting in the federal government partially shutting down for 35 days from December 2018 to January 2019, the longest U.S. government shutdown in history.[330][331] Around 800,000 government employees were furloughed or worked without pay.[332] Trump and Congress ended the shutdown by approving temporary funding that provided delayed payments to government workers but no funds for the wall.[330] The shutdown resulted in an estimated permanent loss of $3 billion to the economy, according to the Congressional Budget Office.[333] About half of those polled blamed Trump for the shutdown, and Trump's approval ratings dropped.