WASHINGTON (AP) — America’s 250th anniversary arrives at a time of deep political divisions and, in some quarters, heightened anxiety over whether representative government in the world’s oldest democracy can be sustained. Cultural institutions , sporting events , even communities are polarized. If there is any place the bitter partisanship is set aside, even temporarily, it is in the rotunda of the National Archives. This is home to the nation’s founding documents, including the one that will