fewest unearned runs allowed in 1 season by team before 2020

Before 2020, the Milwaukee Brewers gave up the fewest runs by a team in a season, with 34 runs in 1884.

	TEAM	R	SEASON	G	W%	W	L	GS	ERA	SO	CG	SHO	SV	IP	H	ER	HR	BB	HBP	IBB	TBF	WP	K/9	BB/9	K/BB	HR/9	K%	BB%	WHIP	BABIP	RA	H/9
1	Brewers	34	1884	12	.667	8	4	12	2.25	139	12		0	104.0	49	26	1	13			386	7	12.03	1.13	10.69	0.09	36.0	3.4	0.60		2.94	4.24
2	Saints	57	1884	9	.250	2	6	9	3.17	44	7		0	71.0	72	25	1	27			320	7	5.58	3.42	1.63	0.13	13.8	8.4	1.39		7.23	9.13
3	Quicksteps	114	1884	18	.111	2	16	18	3.04	113	15		0	142.0	165	48	4	18			625	19	7.16	1.14	6.28	0.25	18.1	2.9	1.29		7.23	10.46
4	Brewers	156	1891	36	.583	21	15	36	2.50	137	35		0	309.2	291	86	6	120	10		1,343	11	3.98	3.49	1.14	0.17	10.2	8.9	1.33	.266	4.53	8.46
5	Orioles	192	1890	38	.441	15	19	38	4.00	134	36		0	315.1	307	140	3	123	24		1,387	13	3.82	3.51	1.09	0.09	9.7	8.9	1.36	.276	5.48	8.76
6	Mountain City	216	1884	25	.240	6	19	25	4.67	93	20		0	219.2	292	114	3	52			1,027	14	3.81	2.13	1.79	0.12	9.1	5.1	1.57		8.85	11.96
7	Brown Stockings	229	1876	64	.703	45	19	64	1.22	103	63		0	577.0	472	78	3	39			2,283	34	1.61	0.61	2.64	0.05	4.5	1.7	0.89		3.57	7.36
8	Red Caps	241	1878	60	.683	41	19	60	2.32	184	58		0	544.0	595	140	6	38			2,225	17	3.04	0.63	4.84	0.10	8.3	1.7	1.16		3.99	9.84
9	White Stockings	257	1876	66	.788	52	14	66	1.76	51	58		4	592.1	608	116	6	29			2,489	3	0.77	0.44	1.76	0.09	2.0	1.2	1.08		3.90	9.24
10	Dark Blues	261	1876	69	.691	47	21	69	1.67	114	69		0	624.0	570	116	2	27			2,536	15	1.64	0.39	4.22	0.03	4.5	1.1	0.96		3.76	8.22
11	Red Caps	263	1877	61	.700	42	18	61	2.15	177	61		0	548.0	557	131	5	38			2,278	20	2.91	0.62	4.66	0.08	7.8	1.7	1.09		4.32	9.15
12	Red Stockings	268	1882	80	.688	55	25	80	1.65	165	77		0	721.1	609	132	7	125			2,977	34	2.06	1.56	1.32	0.09	5.5	4.2	1.02		3.34	7.60
13	Reds	281	1878	61	.617	37	23	61	1.84	220	61		0	548.0	546	112	2	63			2,267	43	3.61	1.03	3.49	0.03	9.7	2.8	1.11		4.61	8.97
14	Grays	288	1877	61	.583	35	25	61	2.25	141	61		0	559.0	617	140	4	41			2,328	20	2.27	0.66	3.44	0.06	6.1	1.8	1.18		4.64	9.93
15	Virginians	294	1884	46	.286	12	30	46	4.52	167	45		0	370.1	402	186	14	52	17		1,634	19	4.06	1.26	3.21	0.34	10.2	3.2	1.23	.280	7.14	9.77
16	Grays	299	1880	87	.619	52	32	87	1.64	286	75		3	799.0	663	146	7	51			3,137	26	3.22	0.57	5.61	0.08	9.1	1.6	0.89		3.37	7.47
17	Dark Blues	311	1877	60	.534	31	27	60	2.32	99	59		0	544.0	572	140	2	56			2,318	18	1.64	0.93	1.77	0.03	4.3	2.4	1.15		5.15	9.46
18	White Stockings	317	1880	86	.798	67	17	86	1.93	367	80		3	775.0	622	166	8	129			3,102	33	4.26	1.50	2.84	0.09	11.8	4.2	0.97		3.68	7.22
19	Brown Stockings	318	1877	60	.467	28	32	60	2.66	132	52		0	541.0	582	160	2	92			2,313	52	2.20	1.53	1.43	0.03	5.7	4.0	1.25		5.29	9.68
20	Blues	328	1878	63	.400	24	36	63	2.32	182	59		1	578.0	621	149	3	87			2,456	30	2.83	1.35	2.09	0.05	7.4	3.5	1.22		5.11	9.67
21	Astros	331	1981	110	.555	61	49	110	2.66	610	23	13	25	990.0	842	293	40	300	11	24	4,034	36	5.55	2.73	2.03	0.36	15.1	7.4	1.15	.261	3.01	7.65
22	White Stockings	331	1878	61	.500	30	30	61	2.37	175	61		0	551.0	577	145	4	35			2,312	38	2.86	0.57	5.00	0.07	7.6	1.5	1.11		5.41	9.42
23	Blues	337	1880	85	.560	47	37	85	1.90	289	83		1	759.2	685	160	4	98			3,100	31	3.42	1.16	2.95	0.05	9.3	3.2	1.03		3.99	8.12
24	Grays	337	1878	62	.550	33	27	62	2.38	173	59		0	556.0	609	147	5	86			2,388	58	2.80	1.39	2.01	0.08	7.2	3.6	1.25		5.46	9.86
25	Yankees	343	1981	107	.551	59	48	107	2.90	606	16	0	30	948.0	827	305	64	287	10	17	3,872	25	5.75	2.72	2.11	0.61	15.7	7.4	1.18	.263	3.26	7.85