It is a common cliché in films: a character flicks through TV channels, seeing the same news story again and again. Pennsylvanians may feel as if their TV sets are mimicking the movies. Donald Trump and Kamala Harris are pouring money into the state. The two campaigns have splurged $189m on advertising there since March, according to the Pittsburgh Post-Gazette, compared with $105m in Michigan, the second-highest spend. The people of Pennsylvania can blame the bombardment on the electoral college, which means that the leader of 330m Americans is chosen by a few thousand voters in swing states.