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How we determine alternate-side parking status

Last verified . Covers the data behind Alternate-side parking.

SuperNYC's alternate-side parking tool tells you whether street-cleaning rules are suspended today — the question New Yorkers with cars ask several times a week. This page documents where the calendar comes from, what we cover, and (importantly) what we deliberately don't cover.

Source: NYC DOT's annual published calendar

Our source of truth is the NYC Department of Transportation's annual published calendar of planned alternate-side parking suspensions. DOT publishes the calendar in two formats:

  • Printable PDF — asp-calendar-2026.pdf. Single-page calendar with the full year's dates, holiday names, and the small-print legal definitions.
  • iCalendar (.ics) — 2026-alternate-side.ics. Machine-readable file containing one VEVENT entry per suspension day with structured DESCRIPTION text. This is the format our implementation ingests because the DESCRIPTION field encodes whether parking meters are also suspended — a distinction the PDF buries in small print.

Both formats produce the same list of dates and reasons. The 2026 calendar contains 37 distinct entries spanning 39 dates total (multi-day observances like Passover and Idul-Adha are counted as separate VEVENTs).

What counts as a suspension

The calendar combines two categories: federal and major legal holidays(six days a year in 2026: New Year's Day, Memorial Day, Independence Day, Labor Day, Thanksgiving, Christmas) and religious and cultural observances (the other ~30 days: Lunar New Year, Ash Wednesday, Passover, Good Friday, Eid al-Fitr, Shavuot, Eid al-Adha, Rosh Hashanah, Yom Kippur, Sukkot, Shemini Atzeret, Simchat Torah, Diwali, and others).

On all of these days, alternate-side parking rules are suspended — the cars parked on the street don't need to move during what would normally be the cleaning window.

The major legal holiday distinction (meters too?)

The PDF small print is what most users actually need to understand. Verbatim from the 2026 calendar:

On MAJOR LEGAL HOLIDAYS, stopping, standing and parking are permitted except in areas where stopping, standing and parking rules are in effect seven days a week (for example, ‘No Standing Anytime’). Accordingly, parking meters will not be in effect on major legal holidays.

The takeaway: on major legal holidays, you can feed less money to a parking meter because they're also suspended. On non-major-holiday suspensions (religious observances, Diwali, etc.), parking meters remain in effect— ASP is suspended but you still need to pay the meter.

Our tool computes the meter-suspension flag by parsing the DESCRIPTION field of each ICS event. The DOT-published text literally includes either "Parking meters will not be in effect" (MLH) or "Parking meters will be in effect" (non-MLH), so we lift the flag directly from the source rather than maintaining a separate list of major legal holidays.

Timezone matters here

The tool's notion of "today" is NYC local time, not the user's browser time. A user opening the page at 11:30 PM Pacific on May 14 (which is 2:30 AM Eastern on May 15) sees the May 15 status, because New York has already crossed midnight. A user opening it at 11:30 PM Eastern on May 14 sees the May 14 status until midnight Eastern.

This matters most around midnight on suspension-day boundaries — if Christmas Day is the next day, our tool will not show "suspended" until the moment it's actually Christmas in New York, regardless of where the user is opening the page.

What this tool does NOT do

Being explicit about scope is part of the methodology:

  • No emergency suspensions.We only show planned suspensions from the annual published calendar. Snow-driven suspensions, parade closures, water-main breaks — none of these are surfaced. See the dedicated discussion below for the rationale.
  • No street-by-street parking sign rules. We don't tell you what the sign in front of your building says. That data requires DSNY's per-segment cleaning schedule (which exists as an open-data CSV) joined to NYC DOT's parking-sign placement data (which is incomplete and updated by hand). That's a separate, much larger project.
  • No meter rate or time-of-day rules.The tool surfaces meter status as a binary suspended/in-effect flag derived from the ICS DESCRIPTION text. We don't display block-level meter rate variations, time-of-day rules, or commercial-vehicle exceptions.
  • No side-of-street logic.The tool answers "is ASP suspended today" — not "which side of the street is being cleaned right now." Side-of-street logic depends on the specific sign at a specific block-face.

Why we don't cover emergency suspensions in v1

This is the most important methodology choice in the tool. Emergency suspensions — snow days, parades, water-main breaks, anything NYC announces in real time — are not surfaced by our v1 implementation. We researched the live data paths and found none of them production-viable for a public, ad-supported tool:

  • NYC 311 Public API (api-portal.nyc.gov): exists and is free, but the parking-calendar endpoint returns a status set that doesn't match what the API actually emits. The community-maintained nyc311calendarPython library has a normalization layer specifically because, in its README's words, the source API is "a mess of poorly named statuses." The API also returns "NO INFORMATION" non-deterministically for dates it should know about, has no published rate limit, and has no documented commitment from the city about uptime or breaking-change notice. Building a publicly-listed tool on top of an undocumented, "messy" city-run endpoint risks shipping incorrect emergency-suspension data the day a snow storm hits — exactly when users would actually rely on it.
  • Third-party scrapers and unofficial endpoints (Twitter parsers, RSS of nyc.gov/dot press releases, scraping the 311 portal HTML): brittle, run afoul of terms of service, and don't degrade gracefully. Not acceptable for production.
  • NYC Open Data: ASP suspensions are not published as a real-time dataset. The historical archive lags by weeks.

The static calendar is, in practice, about 95% of what users actually need — the dominant question is "is alternate-side suspended today or tomorrow?" and ~38 days a year are predictable months in advance. The remaining ~5% (true emergency suspensions) is better served by the user going directly to 311 than by us shipping a flaky guess that might be wrong during the very weather event when they need it most.

For emergency days, we point users at the channels NYC itself maintains in real time:

  • NYC 311 portal — dial 311 from any phone, or visit the portal for the live status banner the city maintains.
  • NotifyNYC SMS alerts — free signup, pushes a text the moment ASP is suspended for weather.

Update cadence

NYC DOT publishes the next year's calendar in November or December. The 2026 ICS file's CREATED field is October 29, 2025 — published about two months before the year starts. We re-fetch in early December, by which point the next year's calendar is reliably available. The PDF and ICS URLs change only the year segment in the filename.

Re-verification schedule

  • NYC DOT 2026 calendar PDF and ICS— re-verified November 2026 (when DOT publishes 2027).
  • Major Legal Holiday definition— re-verified annually with the new calendar. The verbatim text quoted above is updated whenever DOT changes its small-print language.
  • The emergency-suspension upgrade path — revisited whenever NYC publishes a stable webhook or commits to status-set stability on the 311 API. Until that happens, this section is the spec; we don't ship the live path.

Primary sources

See the alternate-side parking status page for the daily check, or read our guide to understanding ASP for a less-technical overview.