Can Trump use 'emergency powers' to build border wall?

Facing stiff resistance from Congress, President Donald Trump has said he might use his emergency powers to construct hundreds of miles of wall on the southern border to prevent migrants from crossing into the United States illegally from Mexico. Trump could indeed declare a national emergency, citing what the administration calls a "crisis" at the border, after nearly 103,000 people were detained in October and November after entering the country illegally. The National Emergencies Act allows the president to declare a national emergency, providing a specific reason for it.