Ǣn trǣg (fram Āncisc trahinere, fram Lātin trahere, 'tō pullian, tō drāwan') is ǣne rǣw wǣgendra fēorhlaþe ðæt rīþ onlang ǣnes rǣlwegas and byrhþ folc oþþe frēol. Trǣgas sindon beclypte oþþe gedrifen bi locmōtas (hātene oft sīmlīċe 'engnas'), þēah sume syndon selfþrāgende, swā-þēah sōþlice ðearfene gecīgede. Fēorhlaþ and byrgend sindon gedrifen on rǣlwagnum, hātene wǣgnum. Trǣgas sindon wundorlicode tō sumum gemete, oþþe byrgenne betwēonan relum. Mǣst trǣgas wyrcad on stǣlwegum mid stǣlwēolum, sē lǣge friċcƿitan ðǣm ƿiċe hiora gelīcost tō oþrum ƿegum būton stǣlwegum.
Trǣgas hæfda hiera wyrttruman on ǣrwegan, ðā ðe gecweden wǣron ƿǣgwegas, ðā syndon dreofende mid horsum oþþe ādrafene mid cabulum. Æfter ƿǣgweges gesƿutelunge on ðǣm Ēnglalande on 1802, trǣgas ƿǣron hrædliċe gebreddode ƿoruldwīd, geunnan fēorhlaþ and fēorh sēcend tō hrādnisse ofer lond ðonne ǣfre ǣr mōgƿiċe. Hrædle gesƿutelung and ƿǣgwegas ƿǣron ƿyrþe ġebǣdu on ðǣm Late 1800um tō gefēran manig folc in and ymbe burhware. Oþþeȝanc, on ðǣm 1920um onbyrigendum ǣfter Wīgƿearde II, dīesel and ǣlces ǣlcum locmōtum tōcūþon steorrum on wǣgen ƿyrþe. Æfter ðǣm gesƿutelunge of wērscipena, ġōðre, and ƿīdgǣða netƿeorcan ðā ēadran fēorhrǣden, swā-þēah hrād flēogan, trǣgas afēaladon on ǣnne ēacwacan ond mǣrƿurþ, and manige relstrǣtƿegas ƿǣron forlǣtene. Ðā ābrec of bysenum lǣdde tō ǣstunga manigra hrædre gesƿutelunga and tramwega under ðīere tide.
Siþþan ðǣm 1970um, ƿigend, middangeardƿīsnere, and trǣgwyrtras beforan trǣgƿistende habbað framsumod tō ġecynde trǣgum ƿegna heora sƿīþran seorƿung and lǣssan heofonƿeardes gasbilǣdenesse ƿiþ ðāra landrīdendra gēocu. Hrædfēorh and trǣgewinnas habbað ƿorðen ǣþel on mǣðe siþþan ðǣm 1970um swā-þēah sēond tōstynt beƿeoƿendlum ǣþelstrǣtum and tō forƿierpendum byggendƿīsn on ðǣm 21. hundǣġe. Fēorhtrǣgas þurh bēaþȝecynd ƿiccað on ceall and ȝeornan, swā-þēah hī synt mēanung mǣstan hrycgenesum ðǣm ƿegum fram hēaȝlicum trīefan and brēac, ġecwēme tō bēaþȝecynde nēa ƿægn and ƿǣðere. Lǣssen ǣfenƿinsum ƿegnescipe ȝecweme tō ġeþolienne tō folc and ȝeornan, sƿā hæfð lǣhte forlǣtan.