Alaska Airlines is pushing passengers to load boarding passes on their smartphones by removing airport kiosks that can be used to print the passes.

The airline has removed kiosks at nine airports so far, and is telling customers to use Alaska’s app to download boarding passes or print them at home.

Alaska executives said Thursday that their goal is to reduce crowding at check-in areas and get passengers to security checkpoints faster. They discussed the issue Thursday during a call with Wall Street analysts to go over first-quarter financial results.

The Seattle-based airline lost $142 million...