MileCheckIs there one API for every state's 511 road alerts?
Not from the states. Each runs its own 511 system with its own developer key and its own limits. Wisconsin's developer page, for example, says calls are throttled to ten every 60 seconds. MileCheck's API returns state DOT alerts for all 50 states in one response shape.
What the states publish
511 Wisconsin documents a REST API for Wisconsin only. It needs a developer key and says "Ten calls every 60 seconds" (read October 31, 2026). Other states use other platforms, other formats and other sign-ups. Some give you a map and no feed.
What MileCheck's API returns
One request for a state returns road conditions and incidents in one shape: closures, crashes, construction and road weather. Each alert names the highway and the location. It carries a mile marker where the state provides one. The response also tells you whether each feed answered, with a source_status field.
GET https://api.milecheckapp.com/v1/alerts?state=WA&apikey=YOUR_KEY
{ "state": "WA",
"counts": { "conditions": 16, "incidents": 184 },
"conditions": [ ... ],
"incidents": [ ... ],
"source_status": { "conditions": "live", "incidents": "live" } }
The endpoints, the fields and the error codes are on the API page.
Coverage, with its limits
Alerts come from a live state feed in all 50 states. Hawaii's feed lists work zones only. A state can show no open incident at a given moment, and the response says so. Each state's agency and source is listed on the data sources page. How often a feed refreshes depends on the state.
What it costs
A test key runs 14 days at 100 calls a day. The Business plan is $299 a month for 100,000 calls. Mile markers are sold separately as a data license. Details are on the plans page.
If you only need one state
Go to that state's 511 developer page. It is free for most states, and you will deal with that state's limits and format yourself.
Get a test key
Email sales@milecheckapp.com for a 14-day test key, or read the endpoint reference first.