▁Research ▁Institute ▁of ▁In fect ious ▁D ise ases ▁( US AM RI ID ). ▁It ▁also ▁hosts ▁the ▁National ▁Can cer ▁Institute - Fre der ick ▁( N CI - Fre der ick ) ▁and ▁is ▁home ▁to ▁the ▁National ▁Inter ag ency ▁Confeder ation ▁for ▁Bi ological ▁Research ▁( N IC BR ) ▁and ▁National ▁Inter ag ency ▁Bi ode f ense ▁Camp us ▁( NI BC ). ▁ ▁Fort ▁Det rick ▁is ▁the ▁largest ▁employ er ▁in ▁Frederick ▁County , ▁Maryland . ▁ ▁History ▁Five ▁far ms ▁originally ▁constit uted ▁what ▁is ▁today ▁known ▁as ▁" Area ▁A " ▁with ▁, ▁or ▁the ▁main ▁post ▁area ▁of ▁Fort ▁Det rick , ▁where ▁most ▁installation ▁activities ▁are ▁located . ▁" Area ▁B " ▁– ▁known ▁as ▁" The ▁Farm " ▁and ▁consisting ▁of ▁nearly ▁ ▁– ▁was ▁purchased ▁in ▁ 1 9 4 6 ▁to ▁provide ▁a ▁test ▁area ▁west ▁of ▁Ros em ont ▁Avenue , ▁then ▁called ▁Y ellow ▁Spr ings ▁Pi ke . ▁In ▁addition , ▁the ▁post ' s ▁water ▁and ▁waste ▁water ▁treatment ▁plants ▁compr ise ▁about ▁ ▁on ▁the ▁banks ▁of ▁the ▁Mon oc acy ▁River . ▁ ▁Det rick ▁Field ▁( 1 9 3 1 – 4 3 ) ▁Fort ▁Det rick ▁traces ▁its ▁roots ▁to ▁a ▁small ▁municipal ▁air port ▁established ▁at ▁Frederick , ▁Maryland , ▁in ▁ 1 9 2 9 . ▁It ▁was ▁operated ▁by ▁a ▁single ▁person ▁and ▁the ▁field ▁was ▁one ▁of ▁a ▁string ▁of ▁emer gency ▁air fields ▁between