What significant activity occurred on August 31, 1890?

The significant activity that occurred on August 31, 1890, was the formation of the Coast Guard. This date marks the establishment of the Revenue Cutter Service, which was a precursor to the modern Coast Guard, merging the duties of revenue collection and enforcement with maritime safety and law enforcement. The Revenue Cutter Service, along with the Life-Saving Service, was eventually consolidated to create the United States Coast Guard in 1915.

The other choices are historically relevant but do not align with this specific date in 1890. The first recorded narcotics seizure did not take place on this date, nor was there a declaration of war by Spain or the start of the Civil War associated with August 31, 1890. The correct context centers around the establishment of a significant maritime enforcement and rescue organization that plays a crucial role in U.S. maritime operations today.