South Dakota State Flag Size Guide: What Size South Dakota Flag Should You Fly?

December 2, 2025

Tidmore Flags — Flag Education Center

From a Sioux Falls porch bracket to a Rapid City commercial flagpole — the 25% rule applied to South Dakota's wind, prairie climate, and setting-by-setting recommendations across East River, West River, and the Black Hills.

2×3 to 8×12 25% Rule East River · West River · Black Hills U.S. Flag Pairing Indoor Sizing

Overview

The Short Answer — and Why South Dakota's Wind Makes It Matter

The most common South Dakota state flag sizes are 3×5 ft for a 20-foot residential pole and 4×6 ft for a 25–30 foot commercial or school pole. For the majority of Mount Rushmore State settings, those two figures are the right starting point. Getting the size exactly right — and choosing a flag material that holds up to South Dakota's demanding climate — requires a bit more context.

South Dakota is one of the windiest states in the country. Huron averages 11.4 mph annual wind speed (NOAA NCDC Comparative Climatic Data); Sioux Falls averages 11.1 mph; Rapid City 12.3 mph. The state's open Great Plains geography and the Black Hills' orographic lift produce persistent wind that is far more punishing to flags than a single precipitation event. South Dakota also experiences some of the most violent weather in the nation — the NOAA 2022 South Dakota State Climate Summary identifies severe thunderstorms, blizzards, High Plains wind events, and hail as statewide hazards. Rapid City recorded a thunderstorm gust of 67 mph on June 10, 2021 (NOAA NCEI Storm Events Database). Flags oversized for their poles are the first casualty in those conditions.

Looking to buy a South Dakota flag? Shop our South Dakota State Flag Collection.

Size your flag correctly for your pole using the 25% rule below, then match material to your exposure level. In South Dakota, both decisions are especially critical.

2×3

House bracket
6 ft arm

3×5

20 ft pole
Most common

4×6

25–30 ft pole
Schools, HOAs

5×8

35–40 ft pole
University, civic

6×10

50–60 ft pole
State buildings

8×12

60–80 ft pole
Highways, arenas

Complete Size Chart

South Dakota Flag Sizes by Pole Height

The table below covers every standard outdoor size from a house-mount bracket to a major highway flagpole. The "Typical South Dakota Setting" column reflects common display scenarios across the state's East River, West River, and Black Hills regions.

Flag Size	Pole Height	Fly ÷ Pole	Typical South Dakota Setting
2×3 ft	6 ft arm / table	—	House-mount bracket (6 ft arm), desktop, boat, parade stick, vehicle mount
3×5 ft Most Popular	20 ft	25%	Standard residential in-ground pole — Sioux Falls neighborhoods, Aberdeen yards, Mitchell-area homes
4×6 ft Common	25–30 ft	24%	HOA entry poles, K–12 schools, small business campuses, county buildings, agri-business facilities
5×8 ft	35–40 ft	25%	University campuses (SDSU, USD, SD Mines, DSU), large commercial properties, county courthouses
6×10 ft	50–60 ft	20–25%	State Capitol in Pierre, major municipal campuses, Rapid City civic centers, tourism destinations
8×12 ft	60–80 ft	20%	Highway commercial poles, I-90 corridor dealership rows, Rushmore-area visitor centers, large event venues

The 25% Rule: The fly end (long dimension) of a flag should equal roughly one-quarter of the pole height. A 20-foot pole → 5 ft fly → 3×5 flag. A 25-foot pole → 6 ft fly → 4×6 flag. Flags sized below 20% of pole height look lost; flags above 30% put excessive stress on hardware — particularly important in South Dakota, where sustained prairie winds average 11+ mph and gusts in severe weather can exceed 60 mph.

Setting-by-Setting Guide

Right-Size Your South Dakota Flag for Where It'll Fly

The 25% rule gives you the correct size for any pole height. These setting cards apply that rule to the most common display scenarios across South Dakota — from a Sioux Falls ranch house to an SDSU campus pole to a Black Hills resort property.

🏠

House-Mount Bracket

2×3 ft on 6 ft arm · 3×5 ft on 8 ft arm

The standard 45-degree bracket on a front porch or garage uses a 6-foot arm — pair it with a 2×3 South Dakota flag. Larger two-story brackets with an 8-foot arm take a 3×5. The flag's fly end should not extend beyond the tip of the arm; an oversized flag wraps around the wall in South Dakota's prevailing southwest winds and wears out at the fly end within a single winter season.

🏡

Residential In-Ground Pole

3×5 ft on 20 ft pole

The 20-foot aluminum or fiberglass pole is South Dakota's standard residential choice — common from Sioux Falls' east-side neighborhoods to Brookings subdivisions and Yankton yards. A 3×5 ft South Dakota flag is the correct size at this height and satisfies the 25% rule exactly. Given the state's average wind speeds, 200-denier nylon is the right material for most sheltered suburban locations; switch to 2-ply polyester on open, exposed lots.

🚜

Rural Farmstead & Acreage

3×5 ft on 20 ft pole · consider 2-ply polyester

Open-country farmsteads across the James River Valley, Coteau des Prairies, and Missouri River breaks face South Dakota's full wind exposure with minimal terrain shelter. Size per the 25% rule — a 3×5 on a 20-foot pole remains correct — but material choice is critical. Open-prairie sites should always fly 2-ply polyester rather than nylon. In blizzard corridors across north-central and northwest South Dakota, inspect grommets and hems at the start of each season.

🏘️

Subdivision & HOA Entry Poles

4×6 ft on 25–30 ft pole

HOA entry monuments and subdivision flagpoles are typically 25–30 feet — common along South Dakota's growing suburban corridors in Minnehaha, Lincoln, and Pennington counties. A 4×6 ft flag satisfies the 25% rule for this height range and provides the presence needed for entry feature display. Use 2-ply polyester for any entry pole in an open or elevated location; nylon for landscaped, sheltered entries.

🏫

Schools & University Campuses

4×6 ft on 25–30 ft (K–12) · 5×8 ft on 35–40 ft (university)

Most South Dakota K–12 schools fly from a 25–30 foot pole — a 4×6 flag is the standard choice statewide. University campuses (South Dakota State University in Brookings, University of South Dakota in Vermillion, SD School of Mines in Rapid City, Dakota State University in Madison) typically fly from 35–40 ft poles, where a 5×8 flag provides the campus presence those poles require. Both sizes are available in institutional quantities.

🏢

Small Business & Commercial

4×6 ft on 25–30 ft · 5×8 ft on 35–40 ft

Retail centers and office parks along South Dakota's commercial corridors — South Minnesota Avenue in Sioux Falls, Mount Rushmore Road in Rapid City, Lacey Street in Aberdeen — typically use 25–30 foot poles (4×6) or 35–40 foot poles (5×8). I-90 corridor dealership rows and large agri-business facilities often use 6×10 on 50–60 foot poles for high-speed highway visibility. Match size to pole height, not visual preference.

🏔️

Black Hills & Tourism Properties

Size per pole · size down one step at ridge and summit sites

The Black Hills — from Deadwood and Lead to Custer and Hot Springs — present a unique combination of elevation (up to 7,242 ft at Black Elk Peak), dense commercial tourism, and orographic wind events. Rapid City averages 12.3 mph annual wind, and ridge-line sites above the valley floor experience considerably higher sustained winds than valley reporting stations reflect. Size per the 25% rule for your pole; at any exposed ridge, summit-facing, or mountain site above 4,000 ft, size down one step and use 2-ply polyester exclusively.

🏛️

Government & Civic Buildings

5×8 on 35–40 ft · 6×10 on 50–60 ft · 8×12 on 60–80 ft

County courthouses across South Dakota's 66 counties typically fly from 35–50 foot poles (5×8). The South Dakota State Capitol in Pierre and major state agency buildings use 50–60 foot poles (6×10). Large event venues and I-90 commercial anchor poles call for 8×12 on 60–80 ft poles. Always confirm the actual pole height before ordering for civic or government display — "flagpole height" estimations are frequently off by 5–10 feet.

🎖️

Indoor & Ceremonial Display

3×5 ft on 7–8 ft pole · 4×6 ft on 8–9 ft pole

Rooms with 8-foot ceilings use a 3×5 flag on a 7-foot indoor pole (leaving clearance for the finial). Offices, school hallways, and civic lobbies with 9–10-foot ceilings accommodate a 3×5 on an 8-foot pole or a 4×6 on an 8–9 foot pole. State Capitol ceremonial chambers and grand halls use a 4×6 flag on a 9-foot pole. Indoor flags use pole-hem sleeves rather than grommets; gold fringe is traditional for formal and ceremonial settings throughout the state.

East River · West River · Black Hills

Regional Notes: South Dakota's Three Distinct Flag-Flying Environments

South Dakota's 77,116 square miles span some of the most climatically distinct terrain in the continental United States — from the humid glacial prairie of East River to the semi-arid High Plains of West River to the forested elevations of the Black Hills. These regions fly different material selections and call for different levels of caution at exposed sites, even when the pole height and flag size are identical.

East River

James River Valley & Glacial Prairie

Sioux Falls · Aberdeen · Watertown · Brookings · Huron · Yankton

Sioux Falls averages 11.1 mph annual wind (NOAA NCDC) and 24.3 inches annual precipitation. Huron averages 11.4 mph wind and 19.9 inches precip (NOAA NCEI 1991–2020 normals). East River's flat glacial terrain offers minimal natural windbreak, meaning flags on exposed suburban lots and rural farmsteads experience the state's full prevailing southwest wind without terrain shelter. Severe thunderstorm events with hail are common in the James River corridor in late spring and summer. Size per the 25% rule; use nylon for sheltered suburban locations, 2-ply polyester for open lots, farmsteads, and any East River site without significant tree or building shelter.

West River

High Plains, Badlands & Missouri Breaks

Rapid City · Pierre · Mobridge · Lemmon · Winner · Faith

Rapid City averages 12.3 mph annual wind — the highest of South Dakota's major cities (NOAA NCDC) — and 16.2 inches annual precip (NOAA NCEI). The High Plains west of the Missouri River experience both summer severe thunderstorm outflow and winter chinook events. Pierre, as the state capital and geographic center, averages 11.3 mph annual wind with frequent spring and fall wind events. West River is South Dakota's most demanding environment for flag longevity. Size per the 25% rule and default to 2-ply polyester for virtually all outdoor West River locations. Nylon is appropriate only for sheltered architectural niches and protected entryways.

Black Hills

Ponderosa Forest, Peaks & Tourism Corridor

Deadwood · Lead · Custer · Hot Springs · Hill City · Spearfish

The Black Hills' elevation range — from ~3,200 ft at Rapid City's western edge to 7,242 ft at Black Elk Peak — creates microclimate variation that standard NOAA city data does not fully capture. Spearfish Canyon and the northern Hills see significant wind channeling. Custer averages 15.4 inches of precipitation (NOAA NCEI), much of it as snow, with the Black Hills receiving up to 200 inches of annual snowfall at higher elevations. For any pole at or above 5,000 ft, size down one step from the 25% calculation (e.g., use a 3×5 where a 4×6 would normally be called for) and fly 2-ply polyester year-round. Valley and canyon floor sites in Deadwood, Lead, and Hot Springs can use standard sizing.

South Dakota Severe Weather Protocol:

South Dakota averages more than 30 tornado events annually and ranks among the top ten states for hail frequency. Severe thunderstorm wind warnings are common across all three regions from May through September. When NWS Sioux Falls or NWS Rapid City issues a Severe Thunderstorm Warning or High Wind Warning for your county, lower your flag if your pole does not have storm-rated hardware. The NOAA NCEI Storm Events Database documents thunderstorm wind gusts of 60–70+ mph at multiple South Dakota locations annually — well above safe continuous-display limits for standard nylon construction. In winter, blizzard conditions across north-central and northwest South Dakota can produce sustained 50 mph winds with near-zero visibility; retrieve flags before any NWS blizzard warning takes effect.

U.S. Flag Display Protocol

Flying the South Dakota Flag with the U.S. Flag

Most South Dakotans display their state flag alongside the U.S. flag — on the same pole or on adjacent poles. U.S. Flag Code and longstanding display protocol govern how the two flags are shown together. Here are the five rules that apply to every combination.

Same Pole (One Halyard)

The U.S. flag must fly at the peak. The South Dakota flag hangs below it on the same halyard. Nothing may be flown above the U.S. flag on the same pole under any circumstances.

Separate Poles

The U.S. flag flies on the pole to its own right — the observer's left as they face the flags. Both poles should be the same height, or the U.S. pole should be taller. The U.S. flag is raised first and lowered last.

Size Rule

The South Dakota flag should be the same size as the U.S. flag when displayed together. Never fly a state flag larger than the U.S. flag on the same display.

Order of Precedence

On a three-pole display — common at South Dakota state and county buildings — the U.S. flag occupies the center position when three flags are displayed at equal height. If heights differ, U.S. flag goes highest.

Half-Staff

When the U.S. flag is at half-staff, the South Dakota flag should also be flown at half-staff. Raise the U.S. flag to the peak first, then lower to half. Reverse order on retrieval.

Indoor Display

South Dakota Flag Sizes for Offices, Schools & Ceremonial Halls

Indoor South Dakota flags use a pole-hem sleeve rather than grommets, and are sized to the room's ceiling height rather than a pole-to-flag ratio. Gold fringe on three sides (all but the hoist) is traditional for formal settings — state offices, county courtrooms, school auditoriums, and civic halls across South Dakota.

Room / Setting	Ceiling Height	Flag Size	Pole Length
Home office, small classroom	8 ft	3×5 ft	7 ft (leave clearance for finial)
Standard office, school hallway, civic club	9–10 ft	3×5 ft	8 ft
Formal office, county courtroom, state agency lobby	9–10 ft	4×6 ft	8–9 ft
Grand hall, auditorium, State Capitol chamber	12 ft+	4×6 ft	9 ft

Gold fringe is optional but conventional for South Dakota courtrooms, the state legislature in Pierre, civic organizations like the American Legion and VFW posts across the state, and any setting where military and ceremonial flags are also present. Indoor flags are not weatherproof and should never be mounted on an outdoor pole.

Complete South Dakota Flag Resource Center

Pair this size guide with our material guide (nylon vs. polyester for your SD location) and South Dakota flag history post.

Material Guide Flag History

Frequently Asked Questions

South Dakota Flag Size: Common Questions

What size South Dakota state flag do I need for a 20-foot pole?

A 3×5 ft South Dakota flag is the standard choice for a 20-foot residential in-ground pole. The flag's fly end (5 ft) equals one quarter of the pole height (20 ft ÷ 4 = 5 ft), satisfying the 25% rule exactly. If your 20-foot pole is in an exposed location — open lot, farmstead, ridge, or any West River property — a 4×6 provides better visible presence while a material upgrade to 2-ply polyester will significantly extend its life against South Dakota's persistent prairie winds.

What size South Dakota flag fits a house-mount bracket?

For a standard 6-foot house-mount arm — the most common porch bracket — choose a 2×3 ft flag. For an 8-foot arm on a two-story home, use a 3×5 ft flag. The flag's fly (long) end should not extend beyond the tip of the mounting arm. An oversized flag wraps the wall in South Dakota's consistent southwest wind and wears out at the fly end faster than one correctly sized for the arm length.

What is the 25% rule for flag sizing?

The 25% rule states that the fly end (longer dimension) of a flag should equal approximately one quarter of the pole's height. A 20-foot pole calls for a 3×5 ft flag (5 ft fly ÷ 20 ft pole = 25%). A 25-foot pole calls for a 4×6 ft flag (6 ft fly ÷ 25 ft = 24%). Flags undersized for their poles look small and limp; flags oversized for their poles put excessive stress on hardware and grommets — a particular concern in South Dakota, where wind-load on oversized flags can loosen pole hardware and tear grommets within a single storm season.

What size South Dakota flag do schools use?

K–12 schools across South Dakota most commonly use a 4×6 ft flag on a 25–30 foot pole. For university campuses — South Dakota State University, University of South Dakota, SD School of Mines, Dakota State University, Dakota Wesleyan — a 5×8 ft flag on a 35–40 foot pole provides the campus visibility those poles require. Indoor classroom display uses a 3×5 ft flag on a 7–8 ft pole with pole-hem sleeve.

Does South Dakota's climate affect which size flag to choose?

Climate affects material choice more than size, but it is relevant at exposed sites. South Dakota ranks among the windiest states in the country — Rapid City averages 12.3 mph annual wind (NOAA NCDC), and open prairie sites frequently experience sustained winds well above that. At exposed farmsteads, Black Hills ridge sites, West River prairie poles, and anywhere prone to blizzard wind events, sizing down one step from the standard 25% calculation and using 2-ply polyester will extend flag life significantly compared to standard nylon.

How do I pair a South Dakota flag with a U.S. flag?

On the same pole, the U.S. flag must fly at the peak — the South Dakota flag below it on the same halyard. On separate poles, the U.S. flag goes on its own right (the observer's left) at the same height or higher. Both flags should be the same size. When the U.S. flag is at half-staff, the South Dakota flag should also be at half-staff — raise the U.S. flag to the peak first, then lower to half-staff position.

What size South Dakota flag is used indoors?

For rooms with 8-foot ceilings, use a 3×5 ft South Dakota flag on a 7-foot indoor pole with pole-hem sleeve. For 9–10 foot ceilings (standard for South Dakota school hallways and offices), use a 3×5 flag on an 8-foot pole or a 4×6 on an 8–9 foot pole. Grand halls and state ceremonial chambers use a 4×6 flag on a 9-foot pole. Gold fringe is traditional for courtrooms, state offices, civic clubs, VFW and American Legion posts, and all formal ceremonial settings.

Tidmore Flags Editorial Staff

Flag Education Center · Tidmore Flags

Tidmore Flags has supplied American-made flags to homes, schools, businesses, and government buildings since 1976. Our Flag Education Center draws on NOAA climate data, U.S. Flag Code, and decades of customer experience across all 50 states.

Sources

NOAA NCDC Comparative Climatic Data — Sioux Falls 11.1 mph, Huron 11.4 mph, Rapid City 12.3 mph, Pierre 11.3 mph annual average wind speed · NOAA NCEI U.S. Climate Normals 1991–2020 — Sioux Falls 24.3 in., Huron 19.9 in., Rapid City 16.2 in., Pierre 17.3 in. annual precipitation (via currentresults.com and NOAA NCEI) · NOAA 2022 South Dakota State Climate Summary (statesummaries.ncics.org) — severe thunderstorms, blizzards, High Plains wind events, hail · NOAA NCEI Storm Events Database — Rapid City thunderstorm wind gust 67 mph June 10, 2021; multiple SD locations 60–70+ mph annual events · SDSU Extension Climatology Office, South Dakota Climate Data — regional precipitation and wind normals, Black Hills elevation and snowfall data · U.S. Flag Code, Title 4 U.S.C. §§ 1–10 — display protocol for paired U.S. and state flags

Shop South Dakota State Flags

Fly the Mount Rushmore State Flag with American-Made Quality

Every South Dakota flag from Tidmore is Made in the USA, FMAA-certified, and available in the size and material right for your location — from a Sioux Falls porch to a Black Hills ridgeline pole.

South Dakota Nylon Flag

200-denier nylon — lightweight, quick-drying, and vivid. The right everyday choice for most sheltered East River residential and suburban settings.

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South Dakota Polyester Flag

Heavy 2-ply polyester built for South Dakota's open prairie, Black Hills ridge sites, West River ranches, and blizzard-corridor farmsteads.

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South Dakota Indoor Flag with Fringe

Pole-hem sleeve with gold rayon fringe on three sides. Traditional for SD courtrooms, state offices, civic clubs, and ceremonial settings.

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South Dakota Indoor Presentation Set

Complete set: fringed nylon flag, oak pole, floor stand, and spear finial. Ready for SD offices, university buildings, and civic facilities statewide.

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U.S. + South Dakota Nylon Bundle

Fly both flags together in matching nylon — correct protocol sizing (both 3×5 or both 4×6) for paired residential or commercial display.

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U.S. + South Dakota Polyester Bundle

Heavy-duty 2-ply polyester pair for exposed SD locations — open prairie farmsteads, commercial poles, and High Plains wind-track settings.

Shop Polyester Bundle

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