Quite unlike Dallas and Fort Worth (which is the model that you inadvertently proposed), Washington and Baltimore do not and never have shared the same cultural interests. And, back when TV markets were first established, Baltimore was considered to be a very big city. It's population has remained relatively stable while Washington has exploded into a top 10 market. However, they have remained distinct - the new DC commuter communities near Baltimore not withstanding.
It's not just a TV thing. Look at sports, culture, food and self-identity. Baltimore, for the most part, has it's own stuff and doesn't depend on Washington much more than Philly depends on New York. It's not just 'blue-collar,' it's also a historic port city. It's more ethnic (like Philadelphia) and far more Catholic than Washington. And (now) far, far less hispanic than the DC market. Culturally and demographically, there are a lot of differences.
If you've ever spent any time in Baltimore, then in Washington (or vice versa), you would no longer be mystified as to why they aren't one market. It's appropriate that they are separate markets.
It's not just a TV thing. Look at sports, culture, food and self-identity. Baltimore, for the most part, has it's own stuff and doesn't depend on Washington much more than Philly depends on New York. It's not just 'blue-collar,' it's also a historic port city. It's more ethnic (like Philadelphia) and far more Catholic than Washington. And (now) far, far less hispanic than the DC market. Culturally and demographically, there are a lot of differences.
If you've ever spent any time in Baltimore, then in Washington (or vice versa), you would no longer be mystified as to why they aren't one market. It's appropriate that they are separate markets.