Keizer is a city in Marion County, Oregon, immediately adjacent to Salem. According to the 2020 Census, the population of Keizer was 39,000 people, a fair fraction compared to the 175,000 people living in Salem. Keizer has been a region for a long time, but it wasn't incorporated as a city until 1982. Since the 1990 Census, Keizer has doubled in population.
Despite being a large enough city, Keizer doesn't have much identity of its own, since it is a suburban area whose retail areas and residential neighborhoods are pretty much indistinguishable from the adjoining parts of Salem. And, in fact, many institutions are shared with Salem, such as having a unified school district. Before I started to write this, I was going to say as a joke that the downtown area of Keizer was the intersection with the Safeway and the Walgreens, but I checked and that is immediately adjoining city hall. Which is not to say it is a terrible place: it has a lot of amenities that suburbs with money have, and it has some nice natural areas along the Willamette River. But like many of the suburban areas that grew up rapidly in the Pacific Northwest after World War II, it lacked much history and character.
Also, despite being only a moderate sized suburb, Keizer is still the 14th largest city in Oregon, and is larger than any other city outside of the Willamette Valley, except for Bend and Medford.