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Commissioner’s Corner

# New Measures of How Widespread Employment Changes Are across States and Metro Areas

Wednesday, August 19, 2020

BLS recently began publishing a new set of measures on employment changes in states and metropolitan areas. For decades we have published monthly estimates of employment, hours, and earnings for each state and metro area. Our new measure summarizes how widespread employment increases or decreases are across all states or metro areas. We call this measure a diffusion index.

What’s a diffusion index? Let me explain how we create the measure.

Let’s say we’re creating a diffusion index for the 50 states and the District of Columbia. We start by assigning each state and D.C. a value depending on whether its employment decreased, stayed the same, or increased over the period we’re looking at.

• The assigned value is 0 if employment decreased.
• The assigned value is 50 if employment stayed the same.
• The assigned value is 100 if employment increased.

The diffusion index is the average of those 51 values. To create a diffusion index for metro areas, we assign values of 0, 50, or 100 for each of 388 metro areas and then average those values. We calculate diffusion indexes for employment changes over 1 month, 3 months, 6 months, and 12 months.

Now that we understand the simple arithmetic for calculating diffusion indexes, what do they mean? An index greater than 50 means more states or metro areas had increasing employment over the period. An index below 50 means more states or metro areas had decreasing employment. At the extremes, an index of 0 means employment fell in all states or metro areas; an index of 100 means employment rose in all of them. A diffusion index of 50 doesn’t necessarily mean 50 percent of the states or areas had increasing employment and the other 50 percent had decreasing employment. It just means the same number of states or areas had increases and decreases, with any of the other states or areas having no change.

The chart below shows 3-month diffusion indexes for all states and metro areas. You can see how all states and nearly all metro areas had job losses during the worst of the 2007–09 recession. We see it again more recently with the downturn associated with the COVID-19 pandemic.

Editor’s note: Data for this chart are available in the table below.

Diffusion indexes aren’t a new analytical tool. We publish other diffusion indexes using national employment data that summarize how employment change is dispersed across industries. The Federal Reserve Bank of Philadelphia publishes diffusion indexes using a variety of data. The new BLS diffusion indexes summarize how employment is changing across geographic areas to give us another perspective of the labor market.

Keep a look out for the new data. We update the indexes each month in our public database.

3-month diffusion indexes for all states and all metropolitan areas
MonthAll statesAll metropolitan areas

Jan 2007

96.177.7

Feb 2007

84.372.2

Mar 2007

84.372.6

Apr 2007

74.559.1

May 2007

86.365.3

Jun 2007

69.661.2

Jul 2007

78.467.7

Aug 2007

74.561.2

Sep 2007

56.951.3

Oct 2007

62.753.2

Nov 2007

79.459.1

Dec 2007

80.463.0

Jan 2008

81.465.3

Feb 2008

78.464.0

Mar 2008

52.050.6

Apr 2008

41.236.2

May 2008

25.529.8

Jun 2008

23.535.4

Jul 2008

16.733.9

Aug 2008

16.729.8

Sep 2008

15.723.6

Oct 2008

7.817.8

Nov 2008

7.811.9

Dec 2008

3.910.1

Jan 2009

2.04.3

Feb 2009

2.03.9

Mar 2009

0.04.1

Apr 2009

0.03.6

May 2009

2.04.9

Jun 2009

3.911.7

Jul 2009

8.814.6

Aug 2009

4.914.0

Sep 2009

5.920.0

Oct 2009

16.728.0

Nov 2009

21.638.5

Dec 2009

19.638.1

Jan 2010

26.538.8

Feb 2010

18.636.0

Mar 2010

70.656.3

Apr 2010

94.174.6

May 2010

100.086.6

Jun 2010

98.079.0

Jul 2010

85.364.3

Aug 2010

35.342.4

Sep 2010

39.244.7

Oct 2010

70.663.7

Nov 2010

74.564.8

Dec 2010

88.273.7

Jan 2011

62.757.0

Feb 2011

76.561.9

Mar 2011

87.367.9

Apr 2011

98.075.5

May 2011

90.267.0

Jun 2011

80.456.4

Jul 2011

83.366.8

Aug 2011

82.472.3

Sep 2011

98.081.8

Oct 2011

82.464.8

Nov 2011

96.166.8

Dec 2011

82.463.1

Jan 2012

88.276.7

Feb 2012

97.178.9

Mar 2012

98.083.1

Apr 2012

96.175.9

May 2012

94.170.0

Jun 2012

70.658.1

Jul 2012

74.557.0

Aug 2012

77.564.4

Sep 2012

86.367.5

Oct 2012

97.176.7

Nov 2012

93.175.4

Dec 2012

90.273.7

Jan 2013

88.270.2

Feb 2013

94.179.5

Mar 2013

99.075.9

Apr 2013

87.375.0

May 2013

82.468.7

Jun 2013

82.468.4

Jul 2013

81.470.6

Aug 2013

94.176.4

Sep 2013

92.277.8

Oct 2013

90.277.8

Nov 2013

94.174.7

Dec 2013

81.473.2

Jan 2014

88.268.7

Feb 2014

80.466.5

Mar 2014

86.373.6

Apr 2014

96.182.0

May 2014

98.083.4

Jun 2014

96.183.5

Jul 2014

96.174.2

Aug 2014

92.274.5

Sep 2014

90.277.2

Oct 2014

98.079.9

Nov 2014

96.179.8

Dec 2014

98.081.8

Jan 2015

93.180.0

Feb 2015

84.374.5

Mar 2015

64.762.5

Apr 2015

74.565.1

May 2015

84.377.1

Jun 2015

84.378.2

Jul 2015

92.284.1

Aug 2015

80.474.5

Sep 2015

86.374.1

Oct 2015

88.275.9

Nov 2015

88.274.6

Dec 2015

88.273.2

Jan 2016

75.571.1

Feb 2016

81.472.4

Mar 2016

78.469.5

Apr 2016

86.377.1

May 2016

72.567.3

Jun 2016

55.957.7

Jul 2016

84.371.3

Aug 2016

86.376.2

Sep 2016

94.185.1

Oct 2016

68.666.9

Nov 2016

82.473.6

Dec 2016

78.464.7

Jan 2017

84.370.0

Feb 2017

79.468.9

Mar 2017

98.076.5

Apr 2017

88.272.0

May 2017

78.468.4

Jun 2017

91.269.6

Jul 2017

80.471.6

Aug 2017

91.275.6

Sep 2017

76.560.8

Oct 2017

80.473.8

Nov 2017

84.370.7

Dec 2017

91.273.8

Jan 2018

90.274.2

Feb 2018

96.180.2

Mar 2018

96.180.9

Apr 2018

86.372.9

May 2018

82.473.6

Jun 2018

94.176.7

Jul 2018

91.281.3

Aug 2018

94.177.2

Sep 2018

82.468.4

Oct 2018

94.172.8

Nov 2018

92.272.3

Dec 2018

88.267.9

Jan 2019

89.279.4

Feb 2019

84.373.3

Mar 2019

82.474.9

Apr 2019

61.856.4

May 2019

64.758.5

Jun 2019

66.755.4

Jul 2019

74.560.8

Aug 2019

80.467.1

Sep 2019

79.466.4

Oct 2019

70.660.3

Nov 2019

68.663.7

Dec 2019

74.567.9

Jan 2020

87.375.9

Feb 2020

86.371.8

Mar 2020

5.929.0

Apr 2020

0.00.0

May 2020

0.00.3

Jun 2020[p]

0.00.6

[p] preliminary