As the final appeals echoed across the land from a long, bare-knuckle campaign, Americans headed for the polls to choose between presidential rivals George Bush and Michael Dukakis, and determine the makeup of the next Congress and the outcome of thousands of races for lesser offices. ``It's in the hands of the gods and the American people,'' said Bush as he completed his final campaign swing Monday. ``I know this race is within our grasp both here and across this country,'' Dukakis told more than 10,000 supporters in Los Angeles.