Where in the world is Mrs. Mervine?

Well, based on the clue "beef, corn, landlocked, U.S., baseball," the place she's at is obviously in the United States. "Landlocked" eliminates the possibility of coastal states. Baseball, to me, eliminates the western states because you don't really hear much about baseball coming from that area. Then I thought, "Wait.. it's not corn AND beef... it's corned beef! Duh!" So I searched "corned beef city" on Google. I got results such as "corned beef and cabbage recipe, a favorite New York food," and "Corned Beef City (A.K.A. Dagenham)," and "Sammy's Famous Corned Beef City in Pittsburgh." I eliminated the Dagenham related one, which left New York and Pittsburgh. Then I began to elaborate less on Pittsburgh and more on New York. New York is home to more than one baseball team... I think... And after searching "corned beef" on Google, I received many results on corned beef and cabbage. I also thought that New York is a common stopover place when you're traveling far away places. But New York isn't landlocked. Well that was a good waste of time. Therefore, I have come to a conclusion that Mrs. Mervine is in Pittsburgh!