A Brief Primer on Amazon's Inbound Network

Drilling down on an important segment of Amazon's distribution network

In this article, I am going to offer a more detailed account of Amazon’s Inbound network than I do in my brief primer on Amazon’s distribution network. Basically every segment of their network has more complexity than I can cover in the brief primer, so maybe I’ll do similar breakouts on their Sortation Center network or the madness of their delivery network.

Amazon Inbound Cross-Docks (IXDs) are the facilities where inventory is received into Amazon’s system, from both ports and domestic suppliers/vendors, and which stock Fulfillment Centers. Once inventory is floating around a robotics floor in a Fulfillment Center, the aim from there is speed. Get it picked, packed, shipped, and delivered licketty split. The inbound logic is also flow-based, but speed is not the imperative; placement is.

If you order something that is only stocked in a Fulfillment Center across the country, and you’re a Prime customer, Amazon’s going to put it on a plane and take a loss if need be - a bad outcome for the company. Much better for them if they can not only predict ahead of time where something is going to be bought and when but also have the logistical capacity on the inbound side to make sure it’s in stock within region at the proper place and time. Never having to put something on a plane is their inbound ideal.

Open the Map of Amazon’s Inbound Network Here

The IXDs all receive inventory into Amazon’s system, but they do so in different ways depending on where they are in the country. 80+% of Amazon imports come in through the west coast, so the west coast IXDs are mostly handling containers. The east coast IXDs, by contrast, are handling some containers from the Ports of NY/NJ, and some that have been routed east from the west coast, but they are also handling more domestic inbound (supposedly a preponderance of domestic inventory comes from suppliers/sellers in New Jersey). Anecdotally, an IXD worker on the east coast said that she mostly sees 53-foot trailers around the facility and fewer ocean-going containers.

In 2024, Amazon instituted a two-tiered cross-dock system, and they did so very quickly. As I cover here, they added about 24 million square feet of IXDs in 2024 alone, many launching in Q4 2024! The cross-docks added that year were mostly national IXDs, and the older system of IXDs were redesignated as regional IXDs. Marc Wulfraat from MWPVL initially floated the theory that the national IXDs were meant to be like Walmart’s Import Distribution Centers, which function as huge storage tanks for imported goods. Given the launch of Supply Chain by Amazon, the company’s play in becoming an end-to-end logistics company for its sellers, as well as the fact that the national IXDs are quite larger than the regional IXDs (1 million square feet on average to the latter’s 600,000 square feet), this made some intuitive sense to me initially. But the new buildings don’t actually seem to be fulfilling any repository role.

Rob Hahn, the COO of Pattern and former operations manager for Amazon Logistics, told me that the national IXD layer was instead intended to solve a problem for suppliers and sellers. Again, for both Amazon and their sellers, it makes sense to stage inventory as close as possible to its eventual destination as predicted from past point of sale data. That requires inventory be placed in multiple IXDs around the country, but it’s much more expensive for sellers to send smaller shipments to 5-6 IXDs than it is to send one large shipment to a single IXD. Thus, the national IXD layer is meant to receive single, large shipments from sellers that they then distribute around the country to regional IXDs.

For Hahn, the national IXD rollout was somewhat disastrous, but it is also conceptually flawed. For him, what Amazon should have done to solve the seller shipment problem was create smaller consolidation points around the country, not to receive inventory into Amazon’s system but simply to batch and route cartons around the country to regional IXDs. Walmart has something like what Hahn describes in its small consolidation nodes for domestic suppliers.

In any event, the two-tiered system is up and running, and I imagine it would be another huge mess to cut bait on it at this point. On the west coast, at least, they probably just needed more inbound capacity, and my guess is that there are/will be plenty of direct national IXD to Fulfillment Center arcs, bypassing the regional IXDs where it makes sense.

In addition to their national and regional IXDs, Amazon also has three special standalone IXDs for Non-Sort items in San Bernardino (CA), Oakley (CA), and Lacey (WA). I’ve also seen these called Import Processing Centers.

They also have “virtual” IXD nodes built into many of their facilities. These are facilities that mainly serve some other function (mostly fulfillment, it seems), but which have one small area of the warehouse devoted to inbound. I am unsure of the capacity of these nodes, but I highly doubt they could adequately serve as a relief valve should the major standalone IXDs be disrupted.

Finally, Amazon utilizes a variety of third-party transloaders around the country. These are facilities that simply serve a routing function - they are the first facility that inbound containers are delivered to, and they route them to IXDs. They will often show up in the Consignee data for Amazon imports, but no inventory is being unpacked at these facilities.