In the UK, aerodrome weather information includes not only QNH (the air pressure at mean sea level), but also QFE, the air pressure at runway level. To arrive at an aerodrome, normally one obtains and sets the altimeter to QFE, so that it reads height above aerodrome level. Then if the circuit (traffic pattern) height is 1000 ft (which it usually is), you just read 1000 ft on the altimeter all the way around the circuit; for a standard overhead join it says 2000 ft; and so on. At any aerodrome the altimeter reads the same thing, because you always set QFE.
I've heard that QFE is not used in the US. Do you just have to work out the circuit height in your head by adding 1000 ft to the published aerodrome level? Or are circuit heights given amsl?