Was the slave trade actually suspended? For how long?
The Articles of Confederation (1777) appear to make no mention of it.
The Constitution of the United States (1789) allowed import of slaves until 1808, whereupon Congress illegalized it. I understand the practice continued.
By the early 19th Century there was little if any importation of slaves into the United States for the simple reason that the existing population of slaves survived long enough, and had enough children, to satisfy domestic demand. The situation in the Caribbean and South America was quite different. There conditions were so brutal that a continual supply was required.
Article 1, Section 9 of the ratified Constitution.
The Migration or Importation of such Persons as any of the States now existing shall think proper to admit, shall not be prohibited by the Congress prior to the Year one thousand eight hundred and eight, but a Tax or duty may be imposed on such Importation, not exceeding ten dollars for each Person.