President Trump has been unwavering in his demands for a wall along the entire 2,000-mile-long U.S. border with Mexico. But Democrats, who control the House of Representatives, have refused to fund it, and in early 2019, this standoff led to the longest government shutdown in U.S. history. Trump declared a national emergency on the border in order to use $2.5 billion in military funds to build the wall. In July 2019, the Supreme Court ruled that the wall’s construction could go ahead while lawsuits challenging Trump’s wall funding work their way through the court system.