When we moved here 3 years ago, we had 6 coniferous trees across our backyard. One was already dead. Over the next 2 years, the trees have died one by one in a row. Now our big holly bushes are dying also. We don't know why. Any ideas?
Is the row of evergreen trees spruce? Blue spruce? Older blue spruce tend to die of a fungal disease known as cytospora canker when the trees get about 25-30 years old. They are not happy with Maryland weather and eventually succumb when weakened by drought. There isn't anything you can ultimately do except remove and replace them with trees better suited to Maryland's climate. Here is information about that: https://extension.umd.edu/hgic/cytospora-canker-spruce
Other than that--which is a guess based upon the fact that we are getting may questions about dying blue spruce these days--we'll need more information to give you a more extensive answer.
There are, of course, many reasons why trees die including disease, insects, and many environmental/cultural situations. Here are photos and information on many: https://extension.umd.edu/hgic/trees-and-shrubs/common-plant-and-pest-problems-trees-and-shrubs You can send us photos of the evergreens, and your hollies, for a better diagnosis.