Thanks to the photographers listed below for their photos available through https://www.flickr.com and Creative Commons licensing. Thank you to the following photographers for their images available under Creative Commons license attribution 2.0 Generic (CC BY 2.0).
Any images available from https://www.needpix.com (a royalty free, public domain images website) are listed specifically.
These credits are not in any particular order.
Image IMG_0308 by Sweet Train
Image Trained Moved by CaptMikey9
Image Train by Ann Baekken.
Image Trains by Nick Nunns. Image no longer available.
Image Trains by Madison Scott-Clary.
Image Female Factory Worker, by James Mcdermott.
Image untitled by The May Firm (Injury Lawyers San Luis Obispo).
Image untitled by Free-Photos (pixabay.com) All pictures are collected on https://needpix.com are from public domain sites and are under the Creative Commons Zero or CC0 Creative Common license.