The 2,000-km-long wall sealing off the US border with Mexico will cost taxpayers $21.6bn, several billions more than earlier estimates, Reuters reports.
The figure is contained in a report commissioned by Department of Homeland Security (DHS) Secretary John Kelly, and has been seen by Reuters, the agency said.
A policy cornerstone of Donald Trump, the wall, which will be a series of fences and walls, was estimated by Trump to cost $12bn during his presidential campaign, and later to cost $15bn by Republican House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell.
Buying private land in order to erect the barrier was one reason for the higher price tag, Reuters said.
Already the US government has begun seeking waivers to address environmental laws on building in some areas, the report indicates. It also depicts the government as having already begun working with contractors, and planning steel purchases.
The US-Mexico border is 3,145km in length, with 1,046km of it already fortified, meaning the new barrier would need to cover more than 2,000km.
According to Reuters the report said the first phase, costed at just $360m, would be modest, targeting sections covering 42km near San Diego, California; El Paso, Texas; and in Texas’s Rio Grande Valley.
Reuters notes that the report does not account for major physical barriers, like mountains, where construction would be difficult.
The report assumes that the Department of Homeland Security would get taxpayer funding approved by Congress by April or May, with construction starting in September.
Trump has insisted that Mexico will reimburse US taxpayers, something Mexico has refused to do.
Image: Border fence between Tijuana, Mexico, on the right, and the US near San Diego on the left, in 2007 (Sgt. 1st Class Gordon Hyde/Wikimedia Commons)