"The Katzenjammer Kids" was the first comic strip to use panels and speech balloons like modern strips do.
Today, comics continue to appear in newspapers all over the world; in the United States on Sundays alone, an estimated 113 million people read the comics, according to King Features Syndicate.
An interesting webpage describing a brief history of comic strips in newspapers. The author of the page brings up how characters like Popeye and Tarzan were created through comic strips in newspapers.
This is a timeline of comic strips in newspapers. This is an important piece to the history of newspapers since it accounts for some of the revenue that physical newspapers create.
One of the saddest casualties of the digital age is the physical newspaper. For me, one of the saddest parts of that larger loss is the likely end of the age of comic strips.