POCOMOKE CITY, Md. — Kelvin Sewell figured he had landed his dream job in 2010, when he retired as a Baltimore police officer to help run the tiny 16-member force in this little riverfront city, which calls itself “the friendliest town on the Eastern Shore.” A year later he became its first African-American police chief.

Blacks and whites have coexisted, sometimes uneasily, in Pocomoke for centuries, but Chief Sewell, with his easygoing manner, quickly fit in. He prodded officers to patrol on foot, pleasing business owners. He helped poor students fill out college applications. Crime, everyone agrees, went down on his watch.

But the chief’s abrupt dismissal in June, without explanation, by a white mayor and majority white City Council that voted along racial lines, has torn Pocomoke asunder, wrecking old friendships and exposing a deep racial rift in this community of roughly 4,100 people, split almost evenly between black and white.

The drama in Pocomoke is a tiny slice of America’s searing national conversation about race, playing out largely in big cities like Baltimore, St. Louis and most recently, Cincinnati, around police mistreatment of African-Americans. A recent New York Times/CBS News Poll found nearly six in 10 Americans, including majorities of blacks and whites, think race relations are generally bad, and nearly four in 10 think they are getting worse.