Black bears can be found throughout much of the Cascade Loop. That said, they are NOT going to be highly visible. Contrary to what many folks thinks, black bears do NOT go looking for humans under normal circumstances. As a matter of fact, they do much of their foraging and movement at night and seek to avoid human contact. Please be watchful and aware if you are hiking through the backcountry. While wildlife is exciting to view, the fact remains that it is indeed wild and can be incredibly dangerous. Understand your environment and how to remain safe before heading out.
Habitat
Bears will most often be found inhabiting forested and mountainous areas. As the seasons change, how bears utilize their environment also changes. Look for bears in areas that green early in Spring--marshlands, etc. In summer and fall expect that bears will be foraging for berries and tree mast crops such as acorns, pine nuts, hazelnuts and black walnuts. Bears will often use hiking trails, logging roads and game trails for travel so again, be aware.
Safety
Whether you are seeking to view or avoid black bears, being safe in the wilderness is essential. Please take time to educate yourself on bear safety before you head out.
Signs of Bears
Whether you are looking for bears or trying to avoid them altogether, knowing the signs to look for in the forest is important.
Where to locate black bears in Washington State
Sources: Western Wildlife Outreach, North American Bear Center, and Wildlife of the Pacific Northwest