Complex sentence: The United States Constitution of 1787 had protected the importation of slaves for twenty years; even so, the Pennsylvania Abolition Society was formed, and held its first meeting at the temporary Capital, Philadelphia, Pennsylvania, in 1794.
Split into simpler sentences: The United States Constitution of 1787 had protected the importation of slaves for twenty years. The Pennsylvania Abolition Society held its first meeting at the temporary Capital, Philadelphia, Pennsylvania, in 1794.