The Numbers Behind Milwaukee Asphalt

Last reviewed 2026-07-25. Journalists, researchers, and community groups are welcome to cite any figure on this page with attribution and a link.

Every figure used elsewhere on this site is collected here with its source. Weather values are NOAA's 1991-2020 U.S. Climate Normals for Milwaukee Mitchell International Airport, station USW00014839. NOAA reports them in tenths, and they are converted to ordinary units below. City figures come from the Department of Public Works, a Common Council district dashboard and news reporting on the city's salt use.

Soil data is from the USDA official series description for the Ozaukee soils and a 1995 engineering study of the Oak Creek till. Housing figures combine the 2020 census with American Community Survey estimates for 2019-2023. Where this page derives a number, such as freeze-thaw days, the arithmetic is shown next to it so anyone can check it against the source.

Freeze-thaw by month at Mitchell Airport

The table below lists each month that records freezing temperatures. A freeze-thaw day here is a day with a low at or below 32 F minus the days whose high also stays at or below 32 F, since a day that never thaws is not a crossing. June through September record none of either, so they are left out. The annual row uses NOAA's annual values, which is why a couple of its totals differ from the monthly sums by a tenth. The freeze-thaw guide explains what these counts do to a driveway.

Source: NOAA NCEI normals-monthly and normals-annualseasonal data for station USW00014839, values divided by ten. Freeze-thaw days are derived as shown.

The warm-season window for sealing and paving

Sealer manufacturers ask for 50 degrees and rising over a 24-hour period, so the overnight low sets the calendar. These are the NOAA values that bracket the season at the airport, with the probability dates given at the 50 percent level, meaning half of years see the event earlier and half later. The sealing season article turns these values into a booking calendar.

Source: NOAA NCEI normals-annualseasonal for USW00014839, fields PRBLST and PRBFST at 50 percent, ANN-TMIN-AVGNDS-LSTH050 and ANN-PRCP-AVGNDS-GE010HI; monthly lows from normals-monthly.

Streets, alleys and salt

The street total differs by source and purpose: the Department of Public Works snow page counts 1,475 miles of city streets for brining, its paving program page works from 1,424 miles, and a Common Council district dashboard rounds to nearly 1,400. The alley and salt figures below explain why private aprons and alley pads take so much abuse and get so little outside help. The post on alley pads and shared drives covers what owners can do about it.

Housing age in Milwaukee and four suburbs

Housing age is a fair proxy for driveway age and lot layout. Milwaukee and its two inner suburbs were largely built before 1960, while Greenfield and Glendale filled in later. Population is from the 2020 census as shown in Census QuickFacts; housing age is from 2019-2023 American Community Survey estimates as tabulated by Point2Homes.

ACS figures are survey estimates with margins of error; decade shares are rounded as published.

Soil beneath the pavement

Two sources describe the ground behind this site's soil discussion. One is the USDA official series description for the Ozaukee soils, a series established in 1966 in the Milwaukee and Waukesha county survey; the other is a 1995 Transportation Research Board paper on the Oak Creek Formation till. Together they explain the perched water and frost heave behind so much local cracking.

• Ozaukee series: moderately well drained, slow permeability
• Loess (wind-blown silt) cap of 0 to 18 inches over dense till
• Dense till begins 20 to 45 inches below the surface
• Perched seasonal water table at 2 to 3.5 feet for a month or more in 6 of 10 years
• Oak Creek till: about 12 percent sand, 53 percent silt, 35 percent clay
• Till thicker than 30 meters in moraines, often under 3 meters between them

Sources & Methodology

Every figure above was taken from the primary sources below (accessed 2026-07-25). Where a number is derived (arithmetic on published figures) or covers a broader period or area, the text says so.

1. NOAA NCEI, 1991-2020 U.S. Climate Normals, annual and seasonal, Milwaukee Mitchell International Airport (USW00014839) — ANN-TMIN-AVGNDS-LSTH032 1255 (125.5 days), ANN-TMAX-AVGNDS-LSTH032 515 (51.5), ANN-SNOW-NORMAL 469 (46.9 in), ANN-TMIN-AVGNDS-LSTH050 2394, ANN-PRCP-AVGNDS-GE010HI 691, PRBLST-T32FP50 04/22, PRBFST-T32FP50 10/23, PRBLST-T36FP50 05/04, PRBFST-T36FP50 10/12.
2. NOAA NCEI, 1991-2020 U.S. Climate Normals, monthly, USW00014839 — MLY-TMAX-NORMAL, MLY-TMIN-NORMAL, MLY-TMIN-AVGNDS-LSTH032, MLY-TMAX-AVGNDS-LSTH032 and MLY-SNOW-NORMAL for each month in the freeze-thaw table.
3. USDA NRCS Official Series Description, Ozaukee series — Loess thickness, depth to densic contact, perched water table depth and duration, series established 1966 in Milwaukee-Waukesha Counties.
4. Edil and Mickelson, Overconsolidated Glacial Tills in Eastern Wisconsin, Transportation Research Record 1479 (1995) — Oak Creek till texture (12 percent sand, 53 silt, 35 clay), thickness and fracture depth.
5. City of Milwaukee DPW, Snow and Ice Control Operations — 1,475 miles of streets brined; alleys not plowed; response times; residents not to push snow into streets.
6. City of Milwaukee, 5th District Dashboard: The Process Behind Road Construction — About 4,000 alleys, eight alley reconstructions a year, 50/50 alley assessment split, 13-15 miles of High Impact paving a year.
7. City of Milwaukee DPW, Local and High Impact Paving Programs — About 40 percent of 1,424 miles of streets need repair; High Impact overlays since 2013; about eight alleys reconstructed each year.
8. CBS 58, Milwaukee DPW says it's ready for winter season (October 31, 2023) — Five-year salt averages of 57,787 and 36,508 tons; salt per inch of snow down from 1,200 to 840 tons.
9. Point2Homes, Milwaukee demographics (ACS 2019-2023) — Median year built 1953 and 34 percent of units built 1939 or earlier; matching pages give the suburb figures.