Thirty-Thousand.org - Correlation Analysis of House Representatives' Reelection Rates vs. Historical House District Sizes

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Correlation Analysis of House Representatives’
Reelection Rates vs. Historical House District Sizes

This analysis evaluates the history of reelected incumbents as a percentage of the total House delegation and how those rates correlate to the average House district sizes historically. The purpose of this analysis is to illustrate:

the reelection trend in the U. S. House of 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%.

This analysis focuses on the number of House seats occupied by Representatives who are reelected from the prior term. 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 percentage of House Representatives which 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 .79. Also shown is the correlation since 1913 (when the size of the House was increased to 435). This correlation factor is .62.

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.

These correlation factors are 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	0.79	10,492	1913	63rd	0.62	2,697
AL	1819	16th	0.43	179	1913	63rd	-0.11	72
AK	1959	86th	0.47	4
AZ	1913	63rd	0.00	29	1913	63rd	0.00	29
AR	1835	24th	0.28	92	1913	63rd	-0.15	51
CA	1851	31st	0.76	334	1913	63rd	0.53	141
CO	1875	44th	0.13	61	1913	63rd	0.02	48
CT	1789	1st	0.28	214	1913	63rd	0.49	74
DE	1789	1st	0.20	61	1913	63rd	0.49	21
FL	1845	29th	0.31	106	1913	63rd	0.36	87
GA	1789	1st	0.43	954	1913	63rd	-0.07	62
HI	1963	88th	0.29	9
ID	1889	51st	0.17	30	1913	63rd	-0.01	25
IL	1817	15th	0.54	450	1913	63rd	0.62	96
IN	1815	14th	0.53	309	1913	63rd	0.23	74
IA	1847	30th	0.38	179	1913	63rd	0.04	79
KS	1861	37th	0.21	113	1913	63rd	0.02	64
KY	1791	2nd	0.54	338	1913	63rd	0.20	43
LA	1811	12th	0.40	154	1913	63rd	0.19	67
ME	1821	17th	0.17	155	1913	63rd	-0.11	38
MD	1789	1st	0.56	278	1913	63rd	0.17	58
MA	1789	1st	0.57	413	1913	63rd	0.21	43
MI	1837	25th	0.61	260	1913	63rd	0.39	103
MN	1857	35th	0.43	128	1913	63rd	0.34	87
MS	1817	15th	0.44	123	1913	63rd	0.04	46
MO	1821	17th	0.58	298	1913	63rd	0.44	76
MT	1889	51st	0.14	32	1913	63rd	0.02	25
NE	1867	40th	0.17	91	1913	63rd	0.22	57
NV	1863	38th	0.22	31	1913	63rd	0.18	19
NH	1789	1st	0.30	143	1913	63rd	-0.01	27
NJ	1789	1st	0.63	309	1913	63rd	0.48	72
NM	1913	63rd	0.32	26	1913	63rd	0.32	25
NY	1789	1st	0.85	1,420	1913	63rd	0.56	47
NC	1789	1st	0.52	321	1913	63rd	-0.10	64
ND	1889	51st	0.23	27	1913	63rd	0.17	21
OH	1803	8th	0.63	635	1913	63rd	0.60	63
OK	1907	60th	0.40	78	1913	63rd	0.40	76
OR	1859	36th	0.54	60	1913	63rd	0.02	39
PA	1789	1st	0.72	1,012	1913	63rd	0.59	60
RI	1789	1st	0.29	72	1913	63rd	0.15	23
SC	1789	1st	0.38	213	1913	63rd	-0.11	50
SD	1889	51st	0.08	35	1913	63rd	-0.07	25
TN	1795	4th	0.57	260	1913	63rd	0.13	61
TX	1845	29th	0.46	238	1913	63rd	0.11	128
UT	1895	54th	0.00	37	1913	63rd	-0.09	33
VT	1791	2nd	0.27	95	1913	63rd	0.08	15
VA	1789	1st	0.48	404	1913	63rd	0.04	44
WA	1889	51st	0.28	75	1913	63rd	0.17	65
WV	1863	38th	0.49	98	1913	63rd	0.42	58
WI	1847	30th	0.52	176	1913	63rd	0.40	89
WY	1889	51st	0.17	17	1913	63rd	0.14	14

Across the states, 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 0.675 (n = 50).

Notes:

The analysis focused only on consecutive terms served by the same congressperson, i.e., in succession without interruption. The numerator for this analysis is the number of Representatives who also served in the preceding term. The numerator includes elected (and reelected) Representatives even if they subsequently did not serve their term for any reason (e.g., death).

The denominator was the number of seats authorized by Congress (for each state) regardless of how many Representatives actually served during that Congress. The number who actually serve was often larger than the number authorized due to turnover (e.g., death or resignation). In a few cases the number who served was fewer than what was authorized (most particularly for those states who temporarily secede to the Confederacy during the 1860s).

The results of this analysis would approximate, but would not be identical to, the percentage of incumbents who seek reelection and win. The latter percentage would be higher in those instances where some incumbents choose not to stand for reelection.

Not reflected in this analysis is the advantage that can be bestowed on an incumbent’s family member (e.g., wife or son) running for that incumbent’s vacant seat.

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