With Portland's population boom, Oregon's elementary schools are becoming ever more filled.

In 1990, some 472,394 students were enrolled at the elementary level. By 2023, the figure is expected to be 626,600, according to the National Center for Education Statistics.

Since 2011 alone, the figure is expected to increase by about 10 percent through 2023, according to NCES researchers.

That's a ton of new students. But, in Oregon's top elementary schools, teachers and administrators appear to be keeping up the good work.

SLIDESHOW: 2018's top 35 elementary schools

Welcome to our second list of the top elementary schools in Oregon and Southwest Washington, as based on ratings by Pittsburgh-based researcher Niche.com. Examining the top K-6 outlets helps indirectly determine several local business metrics, including which areas attract the most real estate development and, of course, which schools feed the smartest students to the next matriculating levels.

A couple of things are different about this year's list.

For starters, Niche ranked all area schools this year, including private offerings. The inclusion of more such schools knocked several other locales out of our list.

Plus, whereas last year we tallied the top 25 Oregon elementary schools, this year, we added another 10 to our roster and, per Niche's research, widened the coverage area to include Southwest Washington schools.

As such, six of the region's top elementary schools, as gauged by several factors, are north of the Oregon border.

Niche examined the schools' academics, quality of teachers and diversity in calculating its grades. Within those metrics, it also graded the schools on student-to-teacher ratios as well as various health and safety measures.

It also pores through state test scores, student-teacher ratio, student diversity and various measures that indicate teacher and school district quality.

Within the expanded list:

  • Bolton Elementary, Willamette Primary and John Muir fell out of the top 10.
  • Riverdale Grade School made the biggest advances among the top-ranked schools.
  • The addition of the Portland area's Caitlin Gabel and Oregon Episcopal to the list also shook up the rankings.

Click through on the picture above to ascertain which elementary schools are, for 2018, Oregon's best.