There are no deadlines. Once you are asked to be a contributor, you may submit pieces at any time. We are writing for a general, well-educated audience. Straight-forward writing is preferred. No academic writing.
Experimental writing is OK if it is accessible.
Ask yourself if someone without a background in your topic would understand your piece. When writing about current events, if the event is not especially well-known by people across the country, you will need to provide a summary so when it is read months or a year later it still makes sense and is relevant. They come from various professions and backgrounds. No material that has been previously published. Fellow contributors and readers will be encouraged to comment on and even attack nonfiction pieces with which they disagree.