Dear Stata users,
I am working on a dataset of firms located in US counties for the years 2000-2018 although not all firms have observations for each year. At some point, in each county there is an election which I have marked as a "treated" dummy taking value 1 for that specific county-year observation and 0 otherwise. Many of these counties are neighboring each other. I want to create another dummy called "neighbor" for example taking value 1 for 5 neighboring counties of the previously mentioned "treated" ones for the year of the election and +1 +2 years. For this I have another file called something like "C\Desktop\neighboring counties" which links each US county to 5 neighbor ones. I report a small extract of each file with dataex. Each county is identified by a code (1073, 1089 and so on). I am using Stata 16.1 by the way. Any help would be much appreciated!

Code:
* Example generated by -dataex-. For more info, type help dataex
clear
input str10 firm_id double Year long county float treated
"098570104" 2000 1073 0
"098570104" 2001 1073 0
"428567101" 2001 1073 0
"098570104" 2002 1073 0
"428567101" 2002 1073 0
"428567101" 2003 1073 0
"098570104" 2004 1073 0
"428567101" 2004 1073 0
"098570104" 2005 1073 1
"428567101" 2005 1073 1
"098570104" 2006 1073 0
"428567101" 2006 1073 0
"098570104" 2007 1073 0
"428567101" 2007 1073 0
"098570104" 2008 1073 0
"428567101" 2008 1073 0
"098570104" 2009 1073 1
"428567101" 2009 1073 1
"098570104" 2010 1073 0
"428567101" 2010 1073 0
"098570104" 2011 1073 0
"428567101" 2011 1073 0
"098570104" 2012 1073 0
"428567101" 2012 1073 0
"098570104" 2013 1073 0
"428567101" 2013 1073 0
"098570104" 2014 1073 0
"428567101" 2014 1073 0
"428567101" 2015 1073 0
"428567101" 2016 1073 0
"428567101" 2017 1073 0
"00738A106" 2000 1089 0
"00738A106" 2001 1089 0
"00738A106" 2002 1089 0
"00738A106" 2003 1089 0
"00738A106" 2004 1089 0
"00738A106" 2005 1089 0
"00738A106" 2006 1089 0
"00738A106" 2007 1089 0
"00738A106" 2008 1089 0
"053893103" 2008 1089 0
"00738A106" 2009 1089 0
"00738A106" 2010 1089 0
"00738A106" 2011 1089 0
"00738A106" 2012 1089 0
"00738A106" 2013 1089 0
"00738A106" 2014 1089 0
"00738A106" 2015 1089 0
"00738A106" 2016 1089 0
"00738A106" 2017 1089 0
end

Code:
* Example generated by -dataex-. For more info, type help dataex
clear
input long(county neighbor)
1001  1021
1001  1047
1001  1051
1001  1085
1001  1101
1003  1025
1003  1053
1003  1097
1003  1099
1003  1129
1003 12033
1005  1011
1005  1045
1005  1067
1005  1109
1005  1113
1005 13061
1005 13239
1005 13259
1007  1021
1007  1065
1007  1073
1007  1105
1007  1117
1007  1125
1009  1043
1009  1055
1009  1073
1009  1095
1009  1115
end