This paper specifies the path in motion events by investigating the grammatical properties and semantic distinction of the three commonly used Mandarin Route markers guò 過 ‘cross/pass’, jīng 經 ‘pass’ and yuè 越 ‘cross’. It further elaborates how morphological makeups reflect semantic details in motion events. According to Liu et al. (2012a), the semantic component Route may be decomposed from the traditional notion of PATH. It denotes the contour of motion without necessarily specifying a direction or endpoint of the path. Route markers serve to introduce the path contour where the figure moves past a landmark, normally specified as a middle point of the path. Unlike Endpoint markers such as dào 到 ‘arrive’ that marks the aimed destination and Direction markers such as wǎng 往 ‘move toward’ that marks the path direction, the Route markers in (1) describe the progressing contour of motion, profiling the process of moving with a locational change: (1) 經風暴，過黑夜，越洋海 jīng fēngbào，guò hēiyè， yuè yanghǎi pass strorm pass dark-night cross sea ‘Pass through the storm,cross the night and the sea.’ These three markers have parallel functions and commonly appear in some syntactic patterns shown as below. (2) a. 過/越/*經 < Route-NP 過/越/*經 [邊界/Route-NP]了 guò /yuè/ * jīng biānjiè le cross boundary ASP ‘(Someone) crossed the boundary.’ b. 過/越/經 < Route-NP < Motion Verb < Loc-NP 過/越/經 [淡水河/Route-NP][到/Motion Verb][對岸/Loc-NP] Guò/ yuè/ jīng dànshuǐhé dào duìàn cross Danshui.River arrive opposite ‘Cross Danshui River to the opposite bank c. Verb < 過/越/經 [飛/Verb]過/越/經 公路 fēi-guò/ yuè/ jīng gonglù fly-cross road ‘Fly over the road.’ These three marker show different grammatical functions in the three syntactic patterns. In Pattern 1, they function as a transitive verb while in Pattern 2, they behave as a typical Route marker, specifying the following noun as the passing landmark and also a prepositional-like coverb, coocurring a motion verb followed by a Loc-NP which referring to a destination of the path. In Pattern 3, the three markers are the second verb in a serial verb construction. It is noted that jīng 經 does not show in Pattern 1, in other words, it cannot function as a transitive verb. A close look of corpus data illustrates that these three markers show different behaviors in each pattern and thus they have distinct grammatical status. Jīng 經 is the least verbal and most like a grammatical marker. Guò 過 is the most verbal and yuè 越 is in between. In addition to grammatical properties, these three markers can be distinguished by their semantic distinction. First, they specify different moving contours. Guò 過 may denote all possible contours (Hsiao 2003, Zeng 2008) while yuè 越 specifies a particular contour ‘go over’. The moving contours in jīng 經 are underspecified and thus jīng 經 may be compatible with various path contours. Besides specifying different contours, guò 過 and yuè 越 are lexically capable of encoding Endpoint while jīng 經 only reflects Route. The two semantic attributes differentiate these three markers and further correlate with their morphological makeups: guò過 can be combined with the other two markers in a fixed sequence so that jīng-guò經過 and yuè-guò越過 are allowed but other combinations are not. The interations between the semantic distictions and two related principles: the spacial sequencing and Mandarin compounding principle account for the ungrammaticality. This study reveals the syntactic and semantic distinctions of the three commonly-used Route markers, illustrating the interesting correlation between lexical semantics and morphological makeups, ultimately further specifying the path in motion events.