It is located east of Beacon Hill; west of Mount Baker, Seward Park, and Leschi; south of the Central District and north of Rainier Beach.

Native Americans had several encampments in the area prior to the settlers, and a permanent village at the south end of the valley.

Two housing projects were completed in the Valley during World War II named; Holly Park and Rainier Vista.

Away from Rainier Avenue South, a fair amount of the development is postwar, when the Valley was filled out as part of the "Boeing boom," but historic pre-World War II housing can be found in every part of the Valley, where these often imposing homes once commanded large spreads that were later subdivided and sold off.

There are several identifiable neighborhoods within Rainier Valley, including (from north to south) "Garlic Gulch" (or the north Valley, from Dearborn to the junction of MLK and Rainier), "Genesee" (from the junction to Alaska), Columbia City (Alaska to Dawson), Hillman City (Dawson to Graham), Brighton (Graham to Kenyon), Dunlap (Kenyon to Cloverdale), and Rainier Beach, which is the only neighborhood in the city where Black Americans make up the majority, at 55%.

Light rail and its attendant improvements (most notably underground wiring) have breathed new life into Martin Luther King Jr. Way South, considered at least since the 1970s beset by "social, physical, and economic blight",[4] tracing difficulties to the Boeing bust – hitting hard in Rainier Valley with its high density of factory workers – and exacerbated by the later construction of a freeway interchange that disrupted a once vital commercial district.

[5] The construction of light rail brought new residential and commercial development to stations at Columbia City and Othello.

"Greater Rainier Valley" can be thought of as including the western slope of Lakewood/Seward Park, and the eastern rise of Beacon Hill.

[9] In 2006, the Seattle Police Department announced that the South Precinct, which includes Rainier Valley had dropped in crime rate by 8% for the first ten months of 2006.