Life, Minnesota, Programming

Does Minnesota really have more shoreline than California?

There’s a popular piece of trivia that says that Minnesota, ostensibly due to 10,000+ lakes, has more shoreline than California. Sometimes, the ante is upped and Minnesota is claimed to have more shoreline than California, Florida, and Hawaii combined. Other times, it’s simply “Minnesota has more than 90,000 miles of shoreline.”

Shoreline of Lake Superior

According to Explore Minnesota Tourism, who used the “more shoreline than California” line in a 2011 television ad, it’s a “commonly-used statistic that was researched and compiled at least 20 years ago by a former advertising agency.” But despite how ubiquitous the factoid has become [1], there’s no definitive proof that it’s true. So: does Minnesota have more shoreline than California? Let’s find out.

Minnesota Shoreline

First, let’s determine the total shoreline in Minnesota. There is no official source for the shoreline of each lake, so we’ll have to get creative. In 1968, the Minnesota Conservation Department published a report titled “An Inventory of Minnesota Lakes” (warning: 498 page PDF). This report included a summary of lakes by size:

lakes-summary

We can use this as a starting point. Lake shorelines are irregular, and the further they deviate from being circular, the more shoreline there is for a given area. But if we assume each lake is a perfect circle, then we can calculate the minimum possible lake shoreline in the state:

Minimum Lake Size, in Acres Minimum Lake Size, in Square Feet Number of Lakes Minimum Circumference of Each Lake, in Feet Minimum shoreline length for this set of lakes, in feet
10 435,600 4,482 2,339 10,486,262
25 1,089,000 3,728 3,699 13,790,968
50 2,178,000 1,892 5,231 9,898,172
75 3,267,000 1,167 6,407 7,477,395
100 4,356,000 765 7,398 5,659,920
125 5,445,000 546 8,271 4,516,442
150 6,534,000 689 9,061 6,243,293
200 8,712,000 1,262 10,463 13,204,538
500 21,780,000 400 16,543 6,617,498
1,000 43,560,000 225 23,396 5,264,187
2,500 108,900,000 63 36,992 2,330,555
5,000 217,800,000 62 52,315 3,243,587
Total Shoreline, in feet 88,732,822
Total Shoreline, in miles 16,805

16,800 miles is the minimum possible shoreline, given lakes of those sizes.

If we had the exact acreage of each lake, we could get a better estimate. Fortunately, that same 1968 report also contains the acreage of each lake! Unfortunately, it’s a PDF of a typewritten document from 45 years ago, and OCR efforts to digitize the table failed. Fortunately, the good folks at the Minnesota DNR provided me with a CSV containing the name of every lake in Minnesota and its last-surveyed acreage! Thanks, DNR! (The spreadsheet with lake sizes is available here.)

Now that we know the exact surface area of each lake, we can do the same “perfect circle” calculations and find that the newest minimum shoreline length is 22,384 miles.

We’re getting closer, but it would be great to not have to rely on the crutch of assuming circular lakes. Isn’t there some way that we can get access to lake dimensions? It’s our lucky day, because the spreadsheet provided by the DNR actually included shoreline measurements. When I said there was no official source for the shoreline of each lake, I fooled you!

According to the DNR, Minnesota has 44,926 miles of lakeshore. (Spreadsheet with data here.) That’s a lot of shoreline, but is it more than California’s?

California Shoreline

I’ve been unable to find a California DNR resource as helpful as Minnesota’s, so we’ll have to take another approach. Where else can we get geographical data about lakes? OpenStreetMap to the rescue!

OpenStreetMap is like Wikipedia for maps, and a service called Geofabrik provides downloads of OpenStreetMap data on a state-by-state basis. (Here’s Minnesota.) The download is an XML file containing all of the information needed to map a given state. Fortunately, we can use a tool called osmfilter to filter the XML file and give us a much smaller file with just the water features.

I wrote a program to parse that file and measure the shoreline of each lake. When I ran my program on the Minnesota data and compared the results to the DNR-supplied data, I found it was off by about 10%:

DNR Shoreline Results compared to OpenStreetMap Shoreline Results
DNR OpenStreetMap
Minnesota 44,926 miles 49,759 miles

It’s mainly because OpenStreetMap includes the entire boundary of some lakes that are only partially in Minnesota.  If I took some time, I could weed those out, but I’m satisfied that this data is close enough for my purposes.

California has 3,427 miles of ocean shoreline as (generously) calculated by NOAA [2], and according to OpenStreetMap, it has an additional 32,050 miles of lakeshore. That’s a total of 35,477 miles of ocean and lake shoreline.

California Shoreline vs. Minnesota Shoreline
Ocean Lakes Total
California 3,427 32,050 35,477
Minnesota 0 44,926 44,926

So yes, Minnesota does have more shoreline than California.

Raising the Stakes

Can Minnesota beat California and Hawaii? Hawaii is practically all shoreline, but because it is so small, it only has 1,052 miles of ocean shoreline [3] and 229 miles of lakeshore. Add that to California’s total, and even at 36,758 miles, it still doesn’t top Minnesota.

California and Hawaii Shoreline vs. Minnesota Shoreline
Ocean Lakes Total
California 3,427 32,050 35,477
Hawaii 1,052 229 1,281
CA + HI 4,479 32,279 36,758
Minnesota 0 44,926 44,926

So yes, Minnesota does have more shoreline than California and Hawaii combined.

Let’s add Florida to the mix. Florida has 8,436 miles of ocean shoreline [4], and according to OpenStreetMap, it has another 22,236 miles of lakeshore. That’s a lot of shoreline, and it increases the tri-state total to 67,430 miles, more than Minnesota.

California, Florida, and Hawaii Shoreline vs. Minnesota Shoreline
Ocean Lakes Total
California 3,427 32,050 35,477
Hawaii 1,052 229 1,281
Florida 8,436 22,236 30,672
CA + HI + FL 12,915 54,515 67,430
Minnesota 0 44,926 44,926

So no, Minnesota does not have more shoreline than California, Hawaii, and Florida combined.

Or does it? We’ve only been considering lakes and oceans, but Minnesota has an additional 69,200 miles of natural rivers and streams [5], both of which have shoreline on each side. That’s an extra 138,400 miles of shoreline, giving Minnesota a grand total of 183,326 miles of shoreline. That’s a lot of shoreline!

Rivers and Streams

According to Wikipedia, Hawaii has about 360 streams [6], the longest of which is 28 miles. Even if we assume they are all 28 miles, that gives Hawaii an additional 10,080 miles of shoreline. (I know it’s bad form to cite Wikipedia, but I think we can agree it’s good enough for this case. And look at that advantage I’m giving Hawaii!)

The Florida Public Service Commission states that Florida has “11,000 miles of rivers, streams & waterways.” [7]

California, according to the California Department of Fish and Wildlife, has 29,664 miles of streams and rivers. [8].

California, Hawaii, and Florida Shoreline vs. Minnesota Shoreline, including Rivers
Ocean Lakes Rivers Total
California 3,427 32,050 59,328 94,805
Hawaii 1,052 229 20,160 21,441
Florida 8,436 22,236 22,000 52,672
CA + HI + FL 12,915 54,515 101,488 168,918
Minnesota 0 44,926 138,400 183,326

California, Hawaii, and Florida combine for an additional 101,488 miles or river shoreline, bringing their grand total to 168,918 miles, which, if you recall, is less than Minnesota’s total of 183,326 miles.

So yes, Minnesota DOES have more shoreline than California, Hawaii, and Florida combined, but only if you consider rivers and streams.

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9 thoughts on “Does Minnesota really have more shoreline than California?

  1. Rick says:

    Great analysis. When you assumed the perfect circle lakes, I was thinking you could probably just double the number for the actual shoreline. Then you found a more accurate number and that assumption would have been close enough!

    One question though – did you add in Lake Superior shoreline? Or remove the shoreline for that particular lake in your numbers? That’s the only lake that probably needs special handling. The other cross state-line-lakes are insignificant (well, maybe Lake of the Woods too).

    • I didn’t manually modify any of the Minnesota DNR data for my final calculations. I don’t believe it included Lake Superior at all, because it classified it as “not in Minnesota”, but I consider it a wash, because it’s offset by the shoreline of rivers that straddle two states, like the lower half of the Mississippi.

      In the grand scheme, those rivers and lakes all only total a couple hundred miles out of the ~180,000 that Minnesota has.

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  4. The DNR report DOES contain the Lake Superior shoreline. Row # 5,664 in the Google spreadsheet.

    Great, great work, by the way! I had heard about the piece of trivia long ago and today was the first day I just searched for some proof, and landed here.

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