Population Change 1990-2000
County or Municipality	2000 Population	1990 Population	Population Change	Percent Change
Pennsylvania	12 281 054	11 881 643	399 411	3.4
Butler County	174 083	152 013	22 070	14.5
Adams township	6 774	3 911	2 863	73.2
Allegheny township	555	504	51	10.1
Brady township	1 452	834	618	74.1
Bruin borough	534	646	-  112	- 17.3
Buffalo township	6 827	6 317	510	8.1
Butler city	15 121	15 714	-  593	- 3.8
Butler township	17 185	17 625	-  440	- 2.5
Callery borough	444	420	24	5.7
Center township	8 182	6 239	1 943	31.1
Cherry township	1 053	814	239	29.4
Cherry Valley borough	72	96	-  24	- 25.0
Chicora borough	1 021	1 058	-  37	- 3.5
Clay township	2 628	2 360	268	11.4
Clearfield township	2 705	2 635	70	2.7
Clinton township	2 779	2 556	223	8.7
Concord township	1 493	1 336	157	11.8
Connoquenessing borough	564	507	57	11.2
Connoquenessing township	3 653	3 093	560	18.1
Cranberry township	23 625	14 816	8 809	59.5
Donegal township	1 722	1 563	159	10.2
East Butler borough	679	725	-  46	- 6.3
Eau Claire borough	355	371	-  16	- 4.3
Evans City borough	2 009	2 054	-  45	- 2.2
Fairview borough	220	224	-  4	- 1.8
Fairview township	2 061	2 009	52	2.6
Forward township	2 687	2 339	348	14.9
Franklin township	2 292	2 156	136	6.3
Harmony borough	937	1 054	-  117	- 11.1
Harrisville borough	883	862	21	2.4
Jackson township	3 645	3 078	567	18.4
Jefferson township	5 690	4 812	878	18.2
Karns City borough	244	226	18	8.0
Lancaster township	2 511	2 268	243	10.7
Marion township	1 330	1 113	217	19.5
Mars borough	1 746	1 713	33	1.9
Mercer township	1 183	1 110	73	6.6
Middlesex township	5 586	5 578	8	0.1
Muddy Creek township	2 267	2 139	128	6.0
Oakland township	3 074	2 820	254	9.0
Parker township	700	601	99	16.5
Penn township	5 210	5 080	130	2.6
Petrolia borough	218	292	-  74	- 25.3
Portersville borough	268	307	-  39	- 12.7
Prospect borough	1 234	1 122	112	10.0
Saxonburg borough	1 629	1 345	284	21.1
Seven Fields borough	1 986	556	1 430	257.2
Slippery Rock borough	3 068	3 008	60	2.0
Slippery Rock township	5 251	4 638	613	13.2
Summit township	4 728	4 284	444	10.4
Valencia borough	384	364	20	5.5
Venango township	732	707	25	3.5
Washington township	1 419	1 280	139	10.9
West Liberty borough	325	282	43	15.2
West Sunbury borough	104	177	-  73	- 41.2
Winfield township	3 585	3 162	423	13.4
Worth township	1 331	955	376	39.4
Zelienople borough	4 123	4 158	-  35	- 0.8
Source: U.S. Census Bureau	Prepared by: Pennsylvania State Data Center