People close to the president say his proclivity to retreat to the residence during work hours has built up over the course of his presidency. In his earliest days in the White House, Trump was especially proud to show off the Oval’s Resolute Desk — a prop he still uses for photo ops and official visitors. Over time, Trump increasingly ditched the formal office and inched closer to the residence — the main building of the White House complex between the East and West wings — where the president and his family keep their private quarters on the second floor, a level above the general tours and official events.

Outsiders can reach Trump there only through the telephone, or if he invites them in.

The president sometimes prefers to interview candidates for high-profile positions from his private quarters, so staff and White House journalists cannot monitor comings and goings. Acting White House chief of staff Mick Mulvaney landed his current job during a late Friday afternoon meeting in the private space of the residence.

It’s been a journey for Trump to settle into his own routine of operating in a White House complex that functions as a historic home, a government headquarters and a museum documenting more than two centuries of history.

Early in this presidency, Trump’s staff tried to nudge him out into the city more often for dinners or to attend events, but the plans always fell apart, said one of the former senior administration officials who called Trump a “homebody.”

On the rare occasion where Trump does venture out in Washington, he dines at his hotel or attends a fundraiser. He recently went to a rare Nationals postseason baseball game with a slew of Republican lawmakers. But most days and nights, if Trump is not on the campaign trail or a foreign trip, he happily stays inside his White House bubble and the residence — working late into the night and very early in the morning.

Trump’s predecessors all used the nation’s most prominent home — which now features 132 rooms and 35 bathrooms across six levels — in their own unique ways.

President Ronald Reagan preferred to read in the evenings in the residence, while President Bill Clinton — like Trump — stayed up late and made calls, said the White House’s former chief usher, Gary Walters, who served in the private residence from Presidents Richard Nixon through George W. Bush.

“They did most of their work in the Oval Office and in the West Wing where they had access to their staff, and there was very little done in the residence,” Walters said.

President George H.W. Bush hosted buffet dinners roughly once a month in the residence for Republican lawmakers, journalists, personal friends and acquaintances, with the first

lady Barbara Bush ringing a bell at the start of the evening to instruct the men to remove their ties.