Northern Brewer was originally bred in England in 1934, and the American-grown strain sold under this name reflects decades of separate cultivation on US soil rather than an entirely distinct breeding program — it's genetically related to, but has diverged somewhat from, hops grown under the same name in Germany, where Northern Brewer also became an important variety in its own right and eventually contributed to Perle's parentage.
At 8-10% alpha acid, the American strain handles bittering duty comfortably while still carrying a woody, mild mint and resinous character that historically made it an important hop in California Common (steam beer) style, one of the few genuinely American-originated beer styles with a documented historical hop preference. Its minty, resinous quality is distinctive enough among American hops that it doesn't overlap closely with the citrus-and-pine vocabulary of the later Cascade-family releases. The American strain's moderate alpha range shouldn't be assumed to match the German-grown Northern Brewer strain exactly — the IBU calculator will show where a bittering charge actually lands. Perle is a reasonable substitute given the shared genetic thread, offering a related minty character from the German breeding side of Northern Brewer's story. Chinook offers an alternative for the resinous, piney side without the mint. California Common and various historical American ale styles use Northern Brewer where its specific woody-mint character is wanted.