When you cut them open, what does the inside look like? You may be dealing with Codling Moths. The moths lay their eggs in the flower and the fruit forms around them. When the larvae hatch, they make themselves at home in the middle of an apple that looks pristine. Then they eat their way out.
It looks like there are a few other apple pests in Maryland. Apple Maggots look likely also.
https://extension.umd.edu/grow...
Even if you don't know what insects might be attacking your apples, spraying is an important part of keeping your trees healthy. I worked on an apple farm back in my misspent youth - the farmers were spraying 6 or 7 times a year! You probably don't need to spray that many times but dormant sprays and then pests sprays are beneficial. This is what Stark Bros. recommend for fruit trees in general.
https://www.starkbros.com/grow...
