互市 is read as ごし (goshi) and means trade.
ごし
goshi
たがい
each other
たがいに
mutually
ごせん
election by mutual vote
たがいちがい
alternate
ごじょ
mutual aid
ごじょかい
benefit society
ごせい
alternate (esp. of leaf arrangement)
とし
town
どうし
same city
いち
market
し
city
みほんいち
trade fair