Everything runs on the grid — and everything runs on people.
Federal policy defines 16 critical infrastructure sectors and oversees them as parallel systems — separate agencies, separate regulations, separate reporting. In reality they form one interdependent web, and in a Black Sky Event that web fails on a clock. This page draws it twice. The ring, below, draws the sixteen sectors by the clock: what stops working first once the grid is gone, and what every one of them stands on. The stack, further down, draws the same web in planning order: what to protect and restore first. Start with the ring.
Sixteen sectors, one foundation, one clock
How to read it. The center is what every sector stands on. The ring is the sixteen sectors, clockwise from the top, in the order they stop working. The outer band is how fast: red in seconds, orange in minutes to hours, yellow in days, green in weeks or more.
The interactive rings need JavaScript. Without it, the sixteen sector rings are shown as images below.
The three disks in the center are the foundation every wedge assumes. Electricity is the built foundation: the grid every sector runs on, and the thing this page assumes is gone. General population is where every sector’s workforce comes from — and where it goes when families cannot survive at home, which is why operators leave their posts before their equipment fails. Governance & security is the lawful order every sector assumes without stating it: the reason a water plant is not looted, a fuel truck arrives, and a shift shows up. Lose the grid and the built tiers stop on the clock shown in the band. Lose the two human layers and nothing above them can be restored at all.
Two things stand out once the ring is read in order. The sectors that stop first are not the lifelines — they are chemical, manufacturing, nuclear, and the defense industrial base, which run entirely on what is beneath them and carry no residual capability of their own. And the lifelines — water, communications, transportation, fuel — hold on longest, not because they are less dependent but because they carry backup power, stored fuel, gravity, and residual stocks that buy hours to days. That gap between what fails first and what everything stands on is the reason the page needs a second drawing.
Ring data: Assessment of Critical Infrastructure with No Grid Power (S. Chill, Foundation for Infrastructure Resilience) — sector definitions, subsector failure timelines, and supporting-infrastructure lists from the 16 Sector-Specific Plans; Appendix A, oil and natural gas (S. Volandt); Appendix B, the Iberian outage of 28 April 2025. Failure times are FIR assessments for the majority of each sector; well-prepared entities will outlast them. Financial services is assessed to fail with communications. Diagram form follows the DHS/NIAC water-dependency wheel.
America runs on a stack — and it fails upward.
The ring shows when each sector stops. The stack shows what each sector stands on — and therefore what has to be protected first and restored first. Energy at the built foundation, lifelines running on energy, shared services running on the lifelines, operations at the top, and beneath all of it the same two human foundations the ring puts at its center. Each sector keeps its dot from the ring, so the two drawings can be read against each other.
The ring already shows what fails first — so why draw a stack?
Because failure order is not restoration order. The ring tells a planner what will stop; the stack tells a planner what to bring back first, which is the order everything else depends on. The same web yields both, and they disagree in exactly the places that matter.
Federal doctrine describes the sectors correctly: PPD-21 treats the 16 sectors as interdependent; the Energy Sector-Specific Plan (§4.2) identifies energy, communications, transportation, and water as the sectors providing lifeline functions to all the others; the National Infrastructure Advisory Council names those same four as the lifeline sectors that warrant top priority for resilience; and FEMA’s Community Lifelines cut across sectors entirely. None of that is in tension with the stack — it is the evidence for it. Trace the web’s dependencies and count their direction: the overwhelming majority run toward energy, water, communications, transportation, fuel, and the finance that pays for all of it. The stack is that count, drawn as a hierarchy.
Read the two drawings together and the disagreement is instructive. The sectors at the top of the stack — chemical, nuclear, manufacturing, the defense industrial base — are the first wedges in the ring. They sit high in planning order because little else stands on them; they stop first because they run entirely on what is underneath. The lifelines sit low in the stack and late in the ring for the same reason, seen from the other side. A community that restores by the ring — bringing back what fell first — will restore the wrong thing first. A community that restores by the stack brings back what everything else needs.
What an honest picture must also show is the traffic running the other way — the feedbacks that make an extended outage a trap rather than a queue:
Thermal generation needs cooling water and emissions control. Lose water pressure and plants that survived the initial event begin shutting themselves down.
Grid operation and restoration run on SCADA and telecom. Cell towers carry 4–8 hours of battery; when they exhaust, operators go blind — including the operators restarting the grid.
Every generator in every tier starts a fuel clock — resupplied by a transportation system that is itself failing.
Treatment plants keep a limited on-site stock of treatment chemicals and depend on routine resupply from the chemical sector — three tiers up.
Fuel, chemicals, food, parts, and crews all move by a system whose pumps, signals, and switching need power. When it halts, every other clock runs out faster.
These feedbacks don’t break the stack — they explain its most important lesson, the restoration trap: the ladder back up burns with the house. A model that were only a hierarchy couldn’t see that. A model that is only a web can’t tell you where to start. The stack with its spine and feedbacks, and the ring with its clock, are built to do both.
Sources: PPD-21, Critical Infrastructure Security & Resilience (2013) · Energy Sector-Specific Plan §4.2 (DOE/DHS) · NIAC lifeline-sector findings · FEMA Community Lifelines · ring timing and dependencies from Assessment of Critical Infrastructure with No Grid Power (S. Chill, FIR) and its oil-and-natural-gas appendix (S. Volandt) · full citations in the FIR threat-assessment volumes.
Three waves — and two clocks
The tiers describe where a sector sits in the dependency structure. The waves describe when its service is lost once the foundation goes. But every wave runs on two clocks at once, and confusing them is how communities get surprised:
The grid fails, and everything wired to it starts a countdown
Generation, transmission, and distribution go together. Every backup system starts a fuel clock. The lifeline tier degrades first because it touches the grid directly — and every failure here removes a tool the tiers above need to respond.
Refineries stop in seconds. Residual pipeline pressure and on-hand fuel buy days; backup generators need resupply within 24–72 hours from a distribution system that is itself failing.
IT fails in seconds with nothing residual. Cell towers carry 4–8 hours of battery; data centers 24–72 hours of fuel. SCADA blinks out with them. Financial services fails on the communications clock: card payments, payroll, and settlement stop together, and cash is honored for a few days — exactly as Iberia showed in April 2025.
Pumped systems — including on-site wells — lose pressure immediately. Treatment needs continuous power plus chemical resupply; most plants carry 24–48 hours of backup. Gravity systems last longer. Contamination and sewage overflow follow.
Fuel pumps, traffic signals, rail switching, and pipeline compressors all need power. Vehicles keep working until their tanks run dry; commercial movement halts within 48–72 hours.
The services people feel — exhausting on the lifelines’ schedule
Tier 2 doesn’t fail because it was attacked. It fails because the lifelines beneath it stopped — and it fails precisely when demand for it spikes. Its degradation starts far earlier than its exhaustion:
Hospitals carry roughly 72 hours of generator fuel — but DHS-surveyed hospitals report ~98% functional degradation within two hours of losing water. Cold chains break; dialysis-, oxygen-, and ventilator-dependent patients are the first mass-casualty event.
The supply chain stops in seconds — no point of sale, no payment, no dispatch. What buys time is residual food already in warehouses, stores, and homes: refrigeration fails in 48 hours; urban grocery empties in 72; larders last weeks.
Government and commercial buildings stop functioning in seconds; the structures remain. 911 keeps its people for weeks but loses dispatch, fuel, and effectiveness within days, as call volume doubles.
The instant failures with the longest shadows
The top of the stack does not fail last — it stops in the first seconds, because it runs entirely on everything beneath it. What arrives last is the consequence: the hazards that build while these plants sit dark, and the restart times that turn a long outage into a long recovery.
Production stops in seconds. Shutdown procedures that fail create hazmat release; on-hand stocks carry the sectors above for weeks; semiconductor, steel, and pharmaceutical restart takes weeks to months after power returns.
Dams are the one resilient sector — manual controls and spillways hold for a month or more, and they are the black-start asset. The DIB stops in seconds with manufacturing; DoD stockpiles buffer the loss, and satellite PNT keeps working until it is damaged.
Reactors shut down in seconds when their load disappears. Seven days of mandated backup fuel serves safety, not output — and spent-fuel pools require cooling for years, so an extended outage with no fuel resupply is a scenario no utility has exercised at scale.
The stack is also the ladder back — and it burns with the house
Restoring the grid requires the tiers above the grid. Replacement transformers take 18–24 months each to build — multi-year when many fail at once — and building them requires critical manufacturing, moving them requires transportation and fuel, installing them requires a workforce whose families are provided for, coordinating all of it requires communications, and all of it requires lawful order. Lose the stack long enough and there is no pathway back. That is why resilience is engineered before the event — from the ground up, tier by tier — not improvised after it.
The whole stack takes the whole nation — in order
No single level of government can protect this structure alone. Federal sector agencies cannot restore sixteen interdependent sectors in thousands of places at once; no community can harden the refinery, the transmission line, or the dependency chains that cross its borders. The stack demands the federated model: national leadership sets the plan and the standard, states prioritize their critical nodes and own readiness within their borders, and Resilient Communities — built to one repeatable template — keep the bottom of the stack alive locally, buying the 30–60 days the rest of the structure needs.
This is not a departure from national doctrine — it is national doctrine, applied to the one catastrophe it hasn’t yet reached. The Tenth Amendment and the Stafford Act structure American disaster response as a tiered escalation: local first, then state, then federal — each level engaged to the extent necessary. PPD-8 declares preparedness the shared responsibility of every level of government, the private sector, and individual citizens; the National Preparedness Goal asks for capability across the whole community. A Black Sky Event is the case where every rung of that ladder is loaded at once — which is exactly why every rung has to be built in advance, in order.
Community resilience is the necessary layer, never the sufficient one — and national planning is what turns thousands of local efforts into one recoverable nation. That is the four-lines-of-effort case, and it is what the FIR Framework, the free assessments, and the state planning work all build toward.