Knock, knock with an app: the US door-to-door campaign ritual

In this Aug. 16, 2018, photo, a campaign worker for Salt Lake County Mayor Ben McAdams holds campaign fliers during door knocking in Mill Creek, Utah. U.S. Rep. Mia Love is battling McAdams for Utah's 4th Congressional District. In conservative Utah, the first black female Republican in Congress is trying to fend off a strong challenge from a well-known Democratic mayor in a largely suburban district where many are wary of President Donald Trump. (AP Photo/Rick Bowmer)

WILKES BARRE, United States: Republican volunteer John Lombardo sets himself an ambitious target when going door-to-door on the campaign trail in battleground state Pennsylvania: a hundred door knocks every two hours. 

In the age of the smartphone and algorithms, door knocking has only cemented itself as a vital way to mobilise US voters, especially those traditionally apathetic when it comes to midterm elections.