Prioritize a 3PL that maps to your delivery promise: start with transit-time targets and required delivery windows, then assess carrier access and frequency. Compare cost-to-serve by SKU (handling, storage, outbound rates) and validate SLAs, peak labor strategies, and integration capabilities to ensure predictable margins under scale.

Look for WMS-driven inventory visibility, multi-temperature storage, cross-dock and consolidation capacity, returns processing, and scalable pick-and-pack operations. Technology integration (EDI/APIs), proven parcel/last-mile relationships, and flexible labor/automation options are essential for omnichannel reliability.

Proximity to port, rail, and major highways reduces dray times and enables higher carrier density, which lowers freight rates and widens scheduling options. Closer access to national networks and regional hubs compresses delivery windows and improves available expedited parcel lanes for last‑mile performance.

Checklist: verify historical peak handling performance, flexible labor sourcing, temporary racking/space availability, surge pricing terms, SLA penalties, insurance and compliance, automation scalability, and IT/API integration timelines to ensure rapid onboarding and consistent KPIs during peaks.