A search of the web often retrieves a number of news articles. One would be forgiven for thinking that all newspapers are freely available on the web. In fact, almost none of them are. Instead, they are releasing some articles to the web (that match your search terms) in order to drive eyeballs to their Ad content and to drive up subscriptions.
Most newspaper sources allow viewing of several articles. Attempts to read more and you will be prompted to subscribe. What you are seeing is frankly, a "teaser" to interest you in purchasing the product.
If you wanted to see how the press's coverage of the tea party, for example, has evolved since it first appeared on the scene, you would have a very difficult time doing this using only the web.
Looking for complete news coverage of a topic? Search the library's news databases.