"A general guide used is whether you have been absent from the United States for more than a year."

"…allows a permanent or conditional permanent resident to apply for admission into the United States during the permit's validity without the need to obtain a returning resident visa…"

"…it is advisable to consider applying for a returning resident visa (SB-1) at the nearest U.S. Embassy or Consulate."

"All persons regardless of citizenship, baggage, and merchandise arriving in, or departing from, the United States are subject to inspection by CBP."