Thirty-Thousand.org - Correlation Analysis of House Representatives' Average Tenure and House District Sizes

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Correlation Analysis of House Representatives’
Average Tenure vs. Historical House District Sizes

This analysis evaluates the history of reelected incumbents’ average tenure in office and how that tenure correlates to the average House district sizes historically. The purpose of this analysis is to illustrate:

the average tenure of U. S. House Representatives; and,
how that trend correlates to House district sizes historically.

During the early 1800s, the average House district size remained below 50,000 (as was intended by the Founding Fathers). Today, the average House district size is over 660,000. As House district sizes grow larger, so does the amount of funding required for a non-incumbent candidate to unseat an incumbent Representative. Consequently, it is easy to understand why reelection rates currently are hovering around 90%.

The Average Tenure in Office is the average number of consecutive years served by all the Representatives holding office. The time period is from the first through the 108^th congresses. See Notes below for additional information regarding the analysis.

Also see Historical Population and U. S. House District Data
for additional data related to the chart above.

The top (blue) graph in the chart above indicates the average tenure (in years) of those House Representatives who were reelected from the previous term (plotted against the right Y-axis). The lower (red) graph is the average size of House districts nationwide (plotted against the left Y-axis).

For each of the graphs, the dashed line graphically illustrate their respective underlying trends as determined by a least squares regression.

The coefficient of correlation between these two graphs is indicated in the table inset in the chart above. For the 108 congresses plotted, the correlation factor is .92. Also shown is the correlation since 1913 (when the size of the House was increased to 435). This correlation factor is .81.

The number of data pairs that comprise each correlation analysis is also provided (“n”). This n value is actually the size of the population; not a sampling.

The coefficient of correlation is also calculated for each state (see table below). However, due to the states’ smaller n values, the correlations become less evident.

Historical
House District Data for
each State

	Since Admission				Since 1913
	Year	Congress	Correl.	n=	Year	Congress	Correl.	n=
US	1789	1st	0.92	10,492	1913	63rd	0.81	2,697
AL	1819	16th	0.66	179	1913	63rd	0.10	72
AK	1959	86th	0.95	4
AZ	1913	63rd	0.37	29	1913	63rd	0.37	29
AR	1835	24th	0.43	92	1913	63rd	0.04	51
CA	1851	31st	0.95	334	1913	63rd	0.85	141
CO	1875	44th	0.16	61	1913	63rd	-0.09	48
CT	1789	1st	0.45	214	1913	63rd	0.61	74
DE	1789	1st	0.39	61	1913	63rd	0.58	21
FL	1845	29th	0.75	106	1913	63rd	0.58	87
GA	1789	1st	0.55	954	1913	63rd	-0.37	62
HI	1959	86th	0.13	9
ID	1889	51st	-0.08	30	1913	63rd	-0.30	25
IL	1817	15th	0.92	450	1913	63rd	0.85	96
IN	1815	14th	0.87	309	1913	63rd	0.71	74
IA	1847	30th	0.61	179	1913	63rd	0.28	79
KS	1861	37th	0.24	113	1913	63rd	-0.09	64
KY	1791	2nd	0.82	338	1913	63rd	0.50	43
LA	1811	12th	0.74	154	1913	63rd	0.42	67
ME	1821	17th	0.07	155	1913	63rd	-0.14	38
MD	1789	1st	0.76	278	1913	63rd	0.34	58
MA	1789	1st	0.84	413	1913	63rd	0.49	43
MI	1837	25th	0.90	260	1913	63rd	0.75	103
MN	1857	35th	0.71	128	1913	63rd	0.53	87
MS	1817	15th	0.75	123	1913	63rd	0.36	46
MO	1821	17th	0.85	298	1913	63rd	0.69	76
MT	1889	51st	0.30	32	1913	63rd	0.23	25
NE	1867	40th	0.53	91	1913	63rd	0.46	57
NV	1863	38th	0.31	31	1913	63rd	0.20	19
NH	1789	1st	0.35	143	1913	63rd	-0.10	27
NJ	1789	1st	0.84	309	1913	63rd	0.61	72
NM	1913	63rd	0.53	26	1913	63rd	0.53	25
NY	1789	1st	0.92	1,420	1913	63rd	0.71	47
NC	1789	1st	0.64	321	1913	63rd	-0.38	64
ND	1889	51st	0.46	27	1913	63rd	0.40	21
OH	1803	8th	0.90	635	1913	63rd	0.83	63
OK	1907	60th	0.33	78	1913	63rd	0.30	76
OR	1859	36th	0.55	60	1913	63rd	0.00	39
PA	1789	1st	0.88	1,012	1913	63rd	0.73	60
RI	1789	1st	0.59	72	1913	63rd	0.34	23
SC	1789	1st	0.66	213	1913	63rd	0.10	50
SD	1889	51st	-0.06	35	1913	63rd	-0.21	25
TN	1795	4th	0.79	260	1913	63rd	0.18	61
TX	1845	29th	0.69	238	1913	63rd	0.27	128
UT	1895	54th	0.13	37	1913	63rd	0.04	33
VT	1791	2nd	0.41	95	1913	63rd	0.20	15
VA	1789	1st	0.61	404	1913	63rd	-0.11	44
WA	1889	51st	0.49	75	1913	63rd	0.37	65
WV	1863	38th	0.83	98	1913	63rd	0.81	58
WI	1847	30th	0.88	176	1913	63rd	0.81	89
WY	1889	51st	-0.10	17	1913	63rd	-0.25	14

There is a clear correlation between n and the the coefficient of correlation. That is, across the states, the larger the population size, n, the larger the coefficient of correlation. In fact, the correlation between the states’ respective n values and correlation factors is 0.50 (n = 50).

Notes:

Average Tenure in Office is the average number of years served by all the Representatives holding office in any given Congress. Tenure is based on the consecutive number of terms a Representative is elected to office. This number is multiplied by two in order to arrive at the total number of years. For example, if the Representative serves only one term, then his duration is two years. If a Representative serves two consecutive terms, then his tenure is four years, and so forth. The data is adjusted to reflect only the authorized number of Representatives rather than the actual total that served during any term (see footnote 2 above). Note: Representatives occasionally do not serve their entire terms (due to death or resignation). Therefore, the actual average tenure may sometimes be slightly less than that calculated.

The source of the data for this analysis was the “Biographical Directory of the United States Congress” [link]. In a number of cases, corrections were made to the table data generated by this resource to be consistent with the biographical descriptions provided by this same resource.

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“If a nation expects to be ignorant and free ...
it expects what never was and never will be.”
– Thomas Jefferson

Created: 15DEC2004

Last updated:15DEC2004